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That One Case

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"The case that makes you and the case that breaks you...The one you never solve, the one that keeps you awake at night. The case that gnaws at your guts and ruins your marriage. The case that keeps you propping up a bar as you relive the what-ifs, the might-have-beens, the half-leads and half-truths. The case that other cops murmur about whenever you walk past. The case you never...ever...discuss."
Herschel Biggs, L.A. Noire

A veteran detective is haunted by that case they could never solve (or perhaps it was "solved" officially, but one of the investigators thinks something doesn't add up) and it haunts them to this day. Nearly always a Serial Killer (or at least an especially gruesome murder) and/or something personal. Even when they are officially off the clock, they will still work the case on their "free" time, because it is that important to them. If they are told to leave the case alone they may get fired over it, but still continue even when they are not a cop any more.

Sub-Trope of My Greatest Failure. Compare Revisiting the Cold Case.

Truth in Television: A number of homicide detectives have solved cold cases that were haunting them or are haunted by the still unsolved ones.


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    Anime & Manga 
  • Case Closed has quite a few of these haunting the police department:
    • Kogoro's One Case ended with a Shoot the Hostage; he quit the police and separated from his wife Eri soon after this. The Non-Serial Movie "The Fourteenth Target" circles around the suspect supposedly taking revenge for this incident.
    • Sato has two One Cases, both of them "inherited": in one, her father perished chasing the suspect from a bank robbery, and in another, she lost her former partner and The Lost Lenore Matsuda to a serial Mad Bomber (who himself had an earlier That One Case that lost his prior partner Hagiwara).
    • Subverted with Megure's That One Case, where a serial hit-and-run driver critically injured both himself and the girl who offered herself up as bait—turns out that was how he met his wife and he's embarrassed to tell the tale since she is both a Former Teen Rebel and much younger than Megure himself. Also, the criminal was caught by the police because of Megure remembering the plate number when he and Midori got hit by the car.
    • Conan himself considers the death of Ai/Shiho's older sister Akemi and his inability to stop the murderer of the Moonlight Sonata from committing suicide his greatest failures.
    • Superintendent Matsumoto has his own That One Case. During a chase following two murders, the biggest suspect of said killings rammed Matsumoto's partner and best friend Morimura with his car; Morimura bled to death in Matsumoto's arms while still trying to relay dying clues. It's really not helped by the culprit being the one who gave Matsumoto his infamous scar across his eyes few later.
  • Runge in Monster believes that Dr. Tenma is a Serial Killer and chases after him relentlessly. It gets to the point where his wife and daughter leave him. By the end of the series, however, he's given a second chance by his daughter.
  • In ERASED, TV reporter Sawada is convinced that the serial child abduction and murders that took place in his town eighteen years ago were not the work of Misunderstood Loner with a Heart of Gold Jun Shiratori but of an experienced killer who had been active in cases prior to and since said murders. He still has a file on the case, which he later shows to Satoru to help him find his mother's (presumably the same) killer.
  • In Magical Girl Lyrical Nanoha StrikerS, Ginga Nakajima (Subaru's big sister) still cannot let go of the "Combat Cyborg incident" that had cost her mother her life eight years prior. The case has been cold ever since because Ginga's own superiors are covering it up—as well as the fact of being in cahoots with the cyborgs' creator and boss, Dr. Jail Scaglietti.
  • The Live-Action Adaptation of JoJo's Bizarre Adventure: Diamond is Unbreakable turns the slaying of the Sugimoto family into this for Josuke's maternal grandfather, Officer Higashikata, to the point where he broke a watch he received from the police department as a reminder of his inability to solve it. In the source material itself, it serves a similar function to the Criminal Minds example mentioned below for Rohan Kishibe, who was the sole survivor.

    Comic Books 
  • Sin City: That Yellow Bastard is all about That One Case for John Hartigan: a serial child rapist/murderer who happens to be the son of one of the most powerful people in Sin City.
  • An occasional form of plot in Batman comics.
    • In Gotham Central, a young detective is dragged into a cold case when the survivor of a horrible school bombing from years before specifically asks for him before killing himself. When he and his partner re-open the case, which had never been solved, they have to bring in Harvey Bullock, the cop who originally worked the case and who has most of the evidence in his personal possession. It is revealed that this is Bullock's One Case, which he claims he "brought home with him" even after he left the force. Bullock's inability to solve the case, even now, pushes him over the edge.
    • In the Nightwing series, Nightwing resolved the One Case of a cop in time for the man's retirement party, so he wouldn't let the unresolved case eat him alive.
    • During the Bruce Wayne: Fugitive? storyline, Batman was called to the bedside of an old dying cop who had been the one to talk to Bruce after he'd witnessed the murder of his parents. The man asked Batman to clear Bruce Wayne's name in memory of the case he'd never been able to resolve, saying that the child he'd seen on that night could not have grown to be a murderer.
    • Similarly, depending on the continuity, the murder of his parents is Batman's One Case. It's referenced in Batman: The Animated Series, The Batman, and Young Justice that Batman wants to prevent the murder of Robin's parents from becoming that one case and ruining his life, too.
  • In The Crow: Curare, Carrie's rape and murder is this for Joe. It ruined his marriage and his life, and that was before the victim rose from the dead to seek revenge...

    Fan Works 
  • one day at a time (Nyame): While Jason Todd managed to mostly succeed in his father's ultimate goal of cleaning up crime in Gotham during his own tenure as Batman, there was still one case he never managed to solve: the Joker Curse. More specifically, figuring out what exactly is causing the death of one Joker to give way to the rise of another Joker. This case was very personal for him, because Jason killed Joker III in his youth, causing the rise of Joker IV, who not only slaughtered almost all of the first Batman's Rogues Gallery, but also murdered Bruce, leading to Dick and later Jason himself becoming Batman. Never solving it was one of Jason's greatest regrets before his death, and when he's forcibly returned to the past, pursuing it again becomes one of his priorities.
  • In Ghoul Detective Series, the death of Kuroto Kai, Kansuke and Yui's childhood idol becomes one. Then, there was the Furinkazan Case. Then, it was revealed that Kaneki was the final part of the Furinkazan strategy. Kai was also part of it as the 'shadow' part of the strategy. It was planned by Tatsue Torada who vowed to make Yui's life a living hell because the latter rejected her son's proposal. She invited Kaneki and the Nagano triad to Nagano so she could kill Kaneki and finish the strategy. The heroes foiled her plan and Kai's soul was finally able to rest in peace, symbolized by the Osmanthus flowers at his grave.

    Films — Animation 
  • This is actually the plot of Scooby-Doo! & Batman: The Brave and the Bold, as Mystery Inc helps Batman solve a case that plagued him since his first year: two of Professor Milo's lab assistants were getting sucked into a portal Milo opened. While Batman rescued one of them (who'd go on to become the Riddler), he failed to save the other.

    Films — Live-Action 
  • In The Darwin Awards, Burrows captures the Serial Killer known as the 'North Side Killer', only for the killer to escape when Burrows faints due to his fear of blood: the whole event being captured on film by a documentary maker. After his dismissal, Burrows becomes obsessed with fixing his mistake and bringing the North side Killer to justice.
  • The titular protagonist Kid Detective (2020) is haunted by the unsolved disappearance of a friend 18 years before the events of the film.
  • The Pledge is based on this premise, with the detective's obsession with his last case eventually driving him insane.
  • Inspector Toschi in Zodiac obsesses over his inability to catch the titular murderer, to the extent that seriously jeopardizes his career. Definitely Truth in Television.

  • Paula Myo chases Adam Elvin and the Guardians of Selfhood in the Commonwealth Saga by Peter F. Hamilton. The case is not so much unsolved as open, because she can't catch the perpetrators - but it is firmly established that it is Paula's only case not closed by an arrest and conviction. The child/gruesome murder angle applies, but not as you might think.
  • The Girl with the Dragon Tattoo features two; the murders of Rebekka Jakobson and Harriet Vanger. Both of the cases were fretted over by different cops, to the same effect; even long into retirement, neither case was solved nor dropped by the head investigator until the titular Salander came along.
  • In Renegades, Adrian is haunted by the unresolved murder of his mother, who died by falling even though she could fly. His arc in the story revolves around finding her killer after he gets the first clue in ten years.
  • In one Hercule Poirot short story, "The Chocolate Box," the Belgian detective tells Hastings about a case early in his career that he actually failed to solve. It's haunted him ever since, because Poirot is something of an Insufferable Genius who absolutely despises making errors. Unlike other examples, justice is somewhat done— the murderer was the victim's mother, she openly confesses to the crime, and she had a very good reason for what she did; she was also terminally ill and said that God would judge her, so Poirot chose to not report the truth to the police—but Poirot still considers it his One Case because he missed an obvious clue and thus didn't succeed.

    Live-Action TV 
  • Cold Case revisits a suspicious death that happened during the Civil Rights era which haunts Jeffries because he grew up in that neighborhood and discovered the victim's body as a boy.
    • The nature of the show gives most of the detectives at least one of these, possibly more.
    • There was also at least one episode where the original investigator of the team's latest cold case was the one who brought it to the team's attention in the first place.
  • The episode "Unfinished Business" of Murder, She Wrote involved a police officer just about to retire who announced he'd be reopening the investigation into the murder of a DA at a resort. He was actually guilty and reopening the investigation as a way to kill a blackmailer and disguise it as an attempt on his life.
  • CSI: NY:
    • One led to Aiden's death. She obtained her one case, got fired after considering forging evidence to put the serial rapist away and in a later episode is killed by said rapist while following him. She is able to leave a bite mark on him (which Mac would think to look for, as she solved a case this way in the past) and her former colleagues are able to put him away.
    • Mac also had one that involved a bodega robbery and the kidnapping of a girl; he finally solved it in the season 7 finale, "Exit Strategy".
  • Monk
    • Trudy's murder is the only one the main character has not solved, and it's haunted him for many years. He only manages to solve it in the Grand Finale. Ironically, he probably could have solved it any time he wanted to. All he had to do was open Trudy's last gift to him.
    • Stottlemeyer has one of his own in one episode. During the investigation of the world's oldest man's death, Stottlemeyer recalls the one case he couldn't solve involving a young man's hit and run death. It turns out that the same man was responsible for both deaths. A second one involves an arson at a golf course.
    • Randy's involves a string of murders committed by a Black Widow, the last of which was from his previous post in Philadelphia.
  • Veronica Mars has this with the Lily Kane case in Season 1.
  • Law & Order: Criminal Intent: Sort of an informed That One Case; Alex's husband was shot in the line of duty, and a later case made a plot point out of the circumstances surrounding said shooting.
    • Nicole Wallace becomes this for Goren. Something of an unusual case in that Goren knows the who and what of the various cases she's involved with; the reason it haunts him is because in spite of all that, he's never been able to hold her accountable or have her punished for her crimes.
  • Law & Order: Special Victims Unit: In "Name", Stabler teams up with a Lab Rat, Millie, when he realizes that the case he's working is related to her deceased father's One Case — the murder of an unidentified Hispanic boy. The case so deeply affected Millie's father that he'd memorized the boy's fingerprints, helped pay for his gravestone, and obsessed over both solving the murder and identifying the victim until he died; after his death, Millie picked up the torch and started looking for answers for him. For perspective, when they realize the connection between the cases, it's the first break in the case — forty years after the murder.
  • Patrick Jane, the main character in The Mentalist deals with the "Red John" case. In his case, the reason It's Personal predates his police work (in fact, he started working with the police to get in on that case); in his former life as a fake TV psychic, he insulted Red John, and Red John retaliated by killing his wife and daughter.
  • In the House episode "All In", House chases the medical case that he was never able to solve: a young boy comes in exhibiting the same symptoms as a patient House earlier lost.
  • Criminal Minds has a couple of these:
    • Agent Ryan, though not a regular, is obsessed with a serial killer case he never solved.
    • Agent Rossi, who is a regular, has been haunted most of his career by the brutal murder of a couple in a house while their children were sleeping, then cleaned the murder weapon and any forensic evidence and left without waking them. It turned out that the killer was a circus clown with a child's mind, who followed the children home to play with them and killed the parents because they frightened him after they found him in the house with a weapon the father was holding; the scene had been cleaned by the father of the clown to avoid sending his handicapped son to jail. They were caught because the clown had been sending childish presents like teddy bears every year to apologize.
    • Hotch has The Boston Reaper. He's closed That One Case now, albeit at great personal cost.
    • Reid had a weird example: the murder of Riley Jenkins. It actually occurred when he was 4 years old and he'd consciously forgotten about it. However, he had a recurring nightmare about investigating the murder of a child, and it turned out to be Riley Jenkins in the dream. When he realized this, he consciously agonized over the case until he solved it.
  • In season one of Frasier, Martin continues to pore over the Weeping Lotus Case—the murder of a young prostitute—even after he retires; toward the end of the season, he gets even more obsessed with the case because the victim's mother is dying and he wants to solve the crime before she goes. Frasier, Niles, and Daphne try to help by looking over the evidence when Martin is out, with Frasier coming to a bizarre yet plausible theory—that the prostitute's ex-boyfriend had his trained chimpanzee kill her. The trio wants Martin to have the satisfaction of solving the case himself, though, so they rearrange the crime scene photos in the hopes that he'll come to the right conclusion. Surprisingly, this works, but not how they intended: they inadvertently move the photos in such a way that makes Martin realize that the real killer was the cop who supposedly discovered the body.
  • In Homicide: Life on the Street, Bayliss had the Adena Watson case.
    • Truth in Television, unfortunately. The real Baltimore child-murder which inspired the Adena Watson storyline was never closed. Getting word out about That One Case is one of the reasons why the real-life Baltimore Homicide Division was supportive of the true-crime book about their work.
  • Inspector Morse has a subverted example: the short story "Morse's Greatest Mystery" is about the "one case he never solved", which is something as minor as someone stealing £20 from a Christmas charity box. Morse claims to have got the culprit, but it turns out he just replaced it with his own money. It turns out the "mystery" of the title refers to the cynical, materialist Morse beginning to understand altruism.
  • Played with in Castle; Det. Beckett's mother was murdered, providing her Freudian Excuse, but she decided to stop looking at her mother's case because it was driving her crazy, and forbids anyone else from looking at it. Still unsolved as of this point. Although Castle did make some headway, he lost Beckett's friendship because of it. Status Quo Is God, however, and getting back together is the emotional subplot of S2E1.
    • As of S2E13, Beckett found the killer, a professional assassin, but was forced to shoot him to save Castle...before he could tell her who had hired him. Castle tries to quit after this incident, but Beckett tells him that she wants him around when they find the employer. Of course, if he tells anyone she said that there will be another shooting...
    • In S6E9, it's revealed that the serial killer known as 3XK is this for Castle.
  • The Fringe episode "Earthling" deals with Broyles's That One Case from years ago that he obsessed over so much it destroyed his marriage. The team eventually solves it, though it turns out to involve a government conspiracy and a Living Shadow radiation-eating alien.
  • The fourth season of Dexter revolves around ex-Agent Lundy trying to track down the "Trinity Killer" who has murdered three people a year for the last fifteen years (later revealed to be four people a year for the past thirty years), who he was never able to convince his colleagues actually existed. After he is killed for getting too close, Debra resolves to solve the case in his honor.
  • The NCIS episode "Lt. Jane Doe" has Ducky cancelling a trip to a conference in Britain to stay and investigate when a murder victim turns out to have a trident mark on her neck (and be a civilian dressed in naval uniform), just like the victim of a 10-year-old unsolved case he worked on which still troubles him as he never managed to identify the original victim and still has her ashes with no family to go to. It turns out that new murder was a crime of passion by the daughter of the original case's lead investigator, and she planted the evidence to link to the older case. The original killer (but not the original victim) is finally identified as a result of the new investigation, having passed away 5 weeks prior. Ducky puts the original Jane Doe's ashes to rest.
  • Cary of Unforgettable is forever haunted by the one case she couldn't solve from her detective work from her home city—the murder of her older sister Rachel. What makes it harder on her is that she saw the killer, but, due to Trauma-Induced Amnesia, that crime scene is the one moment that a woman with otherwise perfect memory cannot remember.
  • The Closer, has Philip Stroh, who Brenda becomes obsessed with. Stroh is a very Amoral Attorney who is also a serial rapist (and as it later turns out, a Serial Killer) who happens to specialize in defending sexual offenders, though this is clearly shown he does this so put all the blame of his crimes on them. Brenda is absolutely certain that he's guilty, but can't prove it and so she starts to follow him around and harass him, and even installs a GPS tracker in his car. Even to the audience, Stroh is incredibly creepy, mostly because as Brenda becomes increasingly desperate to get to him, he never loses his cool and actually seems to enjoy knowing that she's knows what he's done but can't do anything about it. Right up until the end of the series, when he finally does something rash.
  • Bones has Pelant, who seems to keep getting away every time he shows up. And when he went down, he left her with another case threatening to be unending.
  • In the premiere of Golden Boy we are introduced to the case that has been haunting Det Owen for the last eleven years. On the morning of September 11, 2001 a man was murdered and the police investigation quickly found some very promising leads. Then the planes flew into the Twin Towers and in the ensuing chaos the trail went cold. Owen regularly rereads the case file and keeps in touch with the victim's widow.
    • Det Mackenzie is haunted by the unsolved murder of her brother, a police officer killed in the line of duty. While she has been able to partially move on, her retired cop father has been obsessed with the case and is desperate to find his son's killer. The case becomes hot again after the same gun is used in another shooting and this time the killer left evidence the cops can follow. The killer was a mob enforcer and a serial rapist who shot the brother when he interrupted a rape attempt. The victim of the rape was so scared that she fled the city. When she returned a year later, the killer hired a mook to kill her and gave him the same gun. The mook screwed up and killed the witness's sister instead.
  • In True Detective, Cohle is convinced that the 1995 murder case he worked and apparently solved is still unfinished. He continues working it long past its closure, believing that there are additional perpetrators to be found and that the crimes are still ongoing. He's right.
  • In Kamen Rider Double, it's the "Begins Night" case where Shotaro and Philip met and became Double for the first time; but what makes it That One Case for Shotaro is that it was also when his boss and mentor was killed in action.
  • C.D. Parker of Walker, Texas Ranger is met with the reopening of a cold case that retired him in the fourth Season Finale episode "Hall of Fame"— women in general. CD never caught the Hangman because he got checked into a clinic to try and mend his personality, but that failed and he went right back to killings. CD has a proper showdown this time.
  • Harvey Bullock of Gotham has the Goat murders. He caught the guy ten years prior to the start of the series, but his partner got put in a wheelchair in the process. When a killer with the same MO and signature crops up in the present day, the normally-lazy and cynical Bullock suddenly starts taking his job very seriously.
    • In the same series, Jim Gordon, rookie detective, has the Wayne murders. Officially, the killer was Mario Pepper, in whose home was found Martha Wayne's necklace and who was shot by Bullock when he tried to kill Jim, who wanted to interrogate him about it. In fact, Pepper, while a criminal, was framed (with the necklace being a copy), and when Jim learned about it he swore to find the real killer.
  • Supernatural: The detective in "Bloody Mary" (S01, E05) has the Mary Worthingtin murder. Dean references the trope in "Croatoan" (S02, E09), saying that he "feel[s] like this is the one that got away".
  • Murdoch Mysteries: In the aptly-titled "Unfinished Business", Murdoch plays a recording of a man's deathbed murder confession for Dr. Ogden. He's puzzled because the corpse he and his colleagues found by following the man's directions doesn't match other vivid details in the man's statement. Dr. Ogden recognizes the details of the corpse match an early case she worked on; she finds the case file in her old office and expresses regret that she couldn't solve the woman's murder.
  • In the Agent Carter episode "The Lady in the Lake", LAPD Detective Andrew Henry has the "Lady in the Lake Killer", a Serial Killer who killed young women and dumped their bodies into a lake. The killings randomly stopped two years ago and the killer was never brought to justice, so it still eats at Henry so much so that when he's hired to dump the body of a young woman, he copies the killer's MO, as his superiors are trying to get him to drop the case and he needs the public attention to keep the case open.
  • Joe West of The Flash (2014) has the Nora Allen murder case, supposedly committed by her husband Henry Allen. The Allens were good friends with the Wests, and since then Joe has adopted the young Barry Allen as a favor to Henry. Years later, when Barry is now a CSI and finally convinces Joe that someone else has committed the crime, the latter did not hesitate to reopen the case.
  • In the Rizzoli & Isles episode "Boston Strangler Redux" Rizzoli goes looking for a retired cop who worked on the Boston Strangler case. And, as so often happens with retired cops, he has a big brown folder full of files and evidence that he has been keeping all these years just in case someone comes to ask.
  • Without a Trace's Jack Malone has this in the case of a 2-year old boy who vanished six years prior and whose father has hounded him ever since while simultaneously investigating on his own. Vivian Johnson-—who herself has an example of this, as seen in another episode—-explains the circumstances to newcomer Martin Fitzgerald, "We all have our Chet Collinses. You will too."
  • Homicide Hunter Joe Kenda mentions having several of these that still haunt him, 20-something years after he retired. And it's not because he doesn't know who the killer is, it's because he does and doesn't have enough evidence to prove it in court.
  • In the Japanese cop show G-Men '75, Chief Superintendent Tetsuya Kuroki once was involved in an investigation into the brutal killing of a French prostitute that ended with an arrest. When another murder takes place in an all-too-similar manner, he deduces that the real killer got away and is striking again. He takes it upon himself to reopen the case and bring the murderer to justice. Turns out that the initial culprit's son was the real killer, and his father took the fall.
  • While both of Russell Murphy's appearances in RoboCop: The Series revolved around cases he dealt with during his own time as a cop, "Corporate Raiders" was the only one to fit this trope, dealing with a former OCP employee named Tess Stark, who fled years earlier, only to return and go up against the retired Russell and Russell's now cyborg son.
  • One American Police Procedural with a focus on medical examiners had a dead detective that became increasingly obsessed with one of his unsolved cases. However the case was only a couple of years old and it was considered wildly out of character for him. Autopsy revealed that he had undiagnosed Huntington's Disease and the behavior came from the cognitive decline from its progression.
  • Mindhunter: Ford and Tench meet a detective in a small town, racked with a case of a single mother and her child brutally raped and murdered. The detective goes to his grave without solving it, leaving Tench also obsessed with trying to solve it. The BTK case is also this for the runtime of the show.

    Video Games 
  • The Player Character of Disco Elysium has THE SQUARE BULLET HOLE MURDERS. Reading about this mysterious serial murder case (victims shot dead, except the bullet holes are square-shaped and there's no trace of a bullet) reveals that despite the PC's best efforts (and that's really saying something; he's surprisingly good at his job) he never turned up any solid leads or hard evidence and the trail went cold primarily because the killings just suddenly stopped for no discernable reason. If you have the right set of skills in the finale, a Flash Sideways reveals that the killer is preparing to strike again.
  • In Persona 4, the Hierophant social link (and, to a lesser degree, the Justice social link, where it is mentioned in passing) reveal that Ryotaro Dojima's that one case is the hit-and-run that killed his wife.
  • In Fahrenheit, there is Sergeant Mitchell's Kirsten case. Although the murderer has been apprehended on site and convicted, Mitchell later discovered that exactly the same ritualistic murders have been going on for years and nobody batted an eyelash. Needless to say, the murder that Lucas committed and that Carla investigates follows the same pattern. Reeks of an Ancient Conspiracy? There is one.
  • Fallout 4 has two of these cases for Nick Valentine:
    • After you befriend Nick enough, he tells you about the last case that he can remember from before he was made a synth. There was a mobster who had killed his girl but managed to get away with it. You are able to help him bring closure to this case by tracking down the evidence that has survived and locating the now ghoulified mobster.
    • If you go through the files in Nick's office one of them talks about the Mysterious Stranger who Nick assumes is some immortal serial killer. While you cannot talk to Nick about this, should you have the perk and the Mysterious Stranger appears Nick will recognize him and attempt to apprehend him.
  • Episode 4 of Strong Bad's Cool Game for Attractive People, "Dangeresque 3: The Criminal Projective", features a Show Within a Show example: Dangeresque's father was driven mad by his failure to solve a kidnapping case, a plot point that seems to be Strong Bad's excuse to fit Senor Cardgage into his home movie.
  • In L.A. Noire, Phelps actually solves a real life That One Case, the infamous Black Dahlia murder. But you are informed that due to the killer's family connections, he can never reveal the truth.
  • Inspector Juste Volerti of Aviary Attorney has a fixation on finding the Viridian Killer, who in the revolutions eighteen years ago sniped many people and cost Volerti an eye, two legs, and an arm.
  • In Mass Effect, resolving a former cop party member's One Case is an optional sidequest. He actually knows all the relevant information (a Mad Doctor was paying poor people to let him clone organs inside them, leaving the organs if they didn't grow right, and selling the ones that did come out right on the black market), but didn't get to kill the guy during their first encounter.

    Visual Novels 
  • Ace Attorney: Nearly all the games have a major unresolved case that the protagonists ends up dealing with, mostly due to a current murder being related to aforementioned old case.
    • The first game has the DL-6 Incident: the murder of a defense attorney who'd been trapped in a courtroom elevator after an earthquake. Most major characters in the series are somehow affected by this one crime; The victim was Gregory Edgeworth, Miles Edgeworth's father, and the culprit was his mentor Manfred von Karma (who was trying to corrupt Miles into the sort of Amoral Attorney Gregory hated as revenge for Gregory getting him a penalty during a case). Phoenix became a lawyer himself to investigate how his friend Miles had grown up to be a "demon prosecutor", which happened because of his father's death. The culprit of the 4th case, Yanni Yogi, was a suspect in the DL-6 incident who got off via Insanity Defense, ruining his life, and sought to kill his lawyer as revenge (he really was innocent, but his lawyer was sleazy and wouldn't believe him). Misty Fey, the leader of the Fey Clan and mother to Phoenix's mentor Mia and assistant Maya, was called in to use her spirit medium powers to aid in the investigation, but when this failed and the results were leaked to the press, her clan's reputation was dragged through the mud and Misty herself disappeared. Mia also spent most of her career trying to expose Redd White, the guy who'd leaked the information about the channeling, leading to Redd himself killing her. Behind that spoiler tag is a long list of people whose lives were affected (and usually ruined) by this one mystery, which Phoenix has to put to rest in case 1-4 after Edgeworth is proven innocent of the crime he was originally accused of (the aforementioned Yanni Yogi killing his lawyer), but confesses to DL-6 and Phoenix now has to prove him innocent of his father's murder.
    • "Rise from the Ashes" has the SL-9 Incident, which was officially closed 2 years ago, but several detectives who were on that case think something's up. It was known to the public as the Joe Darke Killings, where a Serial Killer who had left no conclusive evidence for his crimes was captured after killing prosecutor Neil Marshall, which provided the evidence needed to get him the death penalty. However, police officer Damon Gant manipulated his partner Lana into framing Joe Darke for Neil's murder (which he actually committed himself, but made it look like Lana's little sister Ema had done). Neil Marshall's brother Jake always thought that something was wrong, and eventually convinced Bruce Goodman (the lead detective on SL-9) to take another look at the evidence, which unfortunately led to Gant killing him to prevent his crime from being uncovered, and Lana forced to take the fall for it. Phoenix gets involved when Ema, convinced her sister was innocent, hires him to defend Lana.
    • Case 3-4 is That One Case for Phoenix's mentor Mia. It's the first case Mia took, and ended in a mistrial. The case traumatized her to the point where she didn't take another for a year. Mia had almost pinned Dahlia Hawthorne for the murder of her half-sister Valerie, but Dahlia was able to get away by manipulating the defendant Terry Fawles into killing himself before he could give crucial testimony that would implicate her. Mia only got back in the game when another case allowed her the opportunity to finally bring Dahlia to justice. In the next case of the game, it's revealed that Edgeworth, who was prosecuting for the first time ever during that case, looks back on it with similar distaste.
    • Apollo Justice: Ace Attorney has the case where Phoenix got disbarred for presenting forged evidence, despite Phoenix being tricked into using it. The case becomes relevant again when the man who claimed to have created the forgery for a client is found poisoned to death.
    • The KG-8 case in Ace Attorney Investigations. The twist is that it actually did get solved (Manny Coachen did it) but the case was dismissed due to the decisive evidence going missing. This is what led Faraday, Badd, and Yew to form the Yatagarasu.
    • Gyakuten Kenji 2:
      • The IS-7 incident, where a pastry chef was found dead on the set of a dessert cooking show. Its investigation is the subject of the third chapter, where Edgeworth has to find a way to both solve the cold case and get around the statute of limitations to catch the murderer, but its shadow hangs over the entire series. Gregory Edgeworth defended the main suspect, Jeffery Masters, and Manfred von Karma was the prosecutor. While Gregory Edgeworth lost the case, he was able to prove that von Karma had extracted illegal testimony from the defendant, which got von Karma his one and only penalty- which directly led to DL-6. The real culprit was also the father of the Big Bad, and the incident was a major contributory factor to said villain's Start of Darkness.
      • The SS-5 Incident; the case where Shi-Long Lang's family name fell into disgrace. It was an assassination of the president of Zheng Fa disguised as a kidnapping, the whole thing plotted by the president's Body Double, who wanted the position of president for himself. Shi-Long Lang's father, Dai-Long Lang, was the president's bodyguard and a member of the Zheng Fa police, so he investigated the crime. But he was stymied by prosecutor Bansai Ichiyanagi/Blaise Debeste, who happened to be in on the assassination and thus manipulated evidence that would have convicted his co-conspirators. However, the conspirators were not in the clear, as the Big Bad happened to be a witness, and their attempts to hunt him down and silence him is what led to his revenge plot against them, and thus the events of the game.
    • Phoenix Wright: Ace Attorney – Dual Destinies has the UR-1 Incident, where Simon Blackquill was convicted of murdering his psychology mentor, Metis Cykes. In reality he did nothing wrong, but the situation painted a bad picture for a young Athena Cykes (Metis' daughter, then a little girl) and he willingly took the fall to protect her. The implications of this case were so strong that this incident, along with Phoenix Wright's disbarment, thrust the legal system into "The Dark Age of the Law", a period of distrust by the public and unscrupulous lawyering tactics on both sides of the courtroom ran rampant; at the same time, however, it became Athena's biggest motivation to become a lawyer, so she can get Simon released. The truth of the incident finally comes out when Simon's older sister, Aura Blackquill, takes several people hostage (including Phoenix's daughter and assistant Trucy) to force a retrial, one day before Simon was to be executed. Not only that, just days before the hostage situation, there was an incident at the space center, the site of the UR-1 murder, where Apollo's friend, Clay, was killed, and Athena just also a suspect in that murder well. Phoenix manages to prove that a third party was responsible for the UR-1 Incident, and that he was also the real killer of Clay as well. The reason behind both murders? The culprit was an international spy known only as the Phantom, who would do anything to eliminate evidence that would reveal his identity.
    • Spirit of Justice has the assassination of queen Amara Sigatar Khura'in, the root of the country's hatred for defense attorneys. 23 years ago, queen Amara, as well as a musician who was performing for her at the time, died in a fire, with the accused being a lawyer who was also charged with forging evidence. Following the incident, the Defense Culpability Act was passed, stating that anyone who dared defend criminals would be deemed just as guilty. In truth, it was part of a scheme by the then-Justice Minister Ga'ran Sigatar Khura'in, to obtain power and keep it unopposed. Ga'ran was the one who started the fire, pinning the blame on lawyer Dhurke Sahdmadhi, and forging evidence for him to unknowingly use. The DC Act was instated to prevent anyone from challenging her. Moreover, Amara didn't actually die in the fire; she was instead kept alive and hostage for Ga'ran to use as needed (as the reason she wasn't Queen before Amara 'died' was because she had no spiritual powers, but Amara did). Even when Dhurke broke Amara out, Ga'ran eventually forced her to return and do her bidding by using Amara's then-newborn daughter as leverage. And the aforementioned unlucky musician was Apollo's biological dad, causing Dhurke to take Apollo in and raise him. Fortunately, Apollo himself is the one who brings the truth to light 23 years later, bringing Ga'ran's reign of terror to an end.
    • The Great Ace Attorney 2: Resolve has the Reaper Organisation and the Professor Killings, which all started with the Lord Chief Justice Mael Stronghart. Growing up in a land where crime ran rampant under the corrupt aristocracy in England, he manipulated Lord Klint van Zieks, a prosecutor, married nobleman, and soon-to-be-father of Iris Wilson, into killing the aristocratic people, using Balmung, the family dog, as a weapon. It was when Klint slew the third of his four victims, a former mentor of his, that he realized that he had been blackmailed into killing the very corrupt aristocrats he was prosecuting, and was Beyond Redemption, becoming known as "The Professor". By the time that Genshin Asogi, one of the foreign exchange students from Japan and Kazuma's father, caught up to Klint after getting sick of Stronghart's baseless conjecture and discovered who Klint really was, he challenged the latter to a Duel to the Death, which Klint gratefully accepted. Resigned to his fate, he wrote his last will and testament confessing everything to his family before dying by Genshin's sword, hoping to end Stronghart's hold on him. However, after Klint's death, Stronghart manipulated the populace into believing that Genshin was the Professor, using trickery though evidence tampering, and had Genshin arrested for five murders. He then brokered a deal with Genshin that he would see his native land and his wife and son again if he would "confess" to the crimes he did not commit, using his staged execution as a means of a jailbreak. Genshin was forced to play along with the manipulation, but on the eve of his "execution", he hid Klint's will inside the hilt of the great sword "Karuma" while writing a message to Kazuma telling him of the ordeal and of the Professor's identity. After Genshin's "execution", Stronghart and Seishiro Jigoku, another exchange student and the Foreign Minister of Justice, planned to get him out of the cemetery near Barclay Prison, but when their plans were foiled by Enoch Drebber, who had witnessed Genshin "rise" from his grave, Stronghart manipulated Jigoku into killing Genshin by fatally shooting him in the back. Afterward, he attempted to cover up the whole affair by having Asogi's message confiscated in his effort to find Klint's will, having the prison warden fired for the plot in the attempted jailbreak, and sending Jigoku and Professor Yujin Mikotoba back to Japan under the implication that Genshin "died of a disease". As if that wasn't enough, as the years went on, Stronghart implicated Klint's younger brother Barok to prosecute corrupt criminals and bring them to justice (and then, if any were acquitted, Stronghart would have them killed one way or another); using deception and manipulation, he and Jigoku started an assassin exchange and used Genshin's son Kazuma, as well as a Femme Fatale named Asa Shinn, as pawns to kill two important men involved in the Professor killings (Inspector Tobias Gregson and Dr. John H. Wilson) to further cover up the truth. After 10 years of deceptions, maniuplations, and cover-ups, it took the efforts of a certain Ryunosuke Naruhodo and Herlock Sholmes and all their friends (including Queen Victoria herself!) to finally bring that case to a close once and for all.