Carrie Eldridge: You lied to me? She can't do that, can she?!
: (to Olivia) You lying bitch! I hate you!
When a detective tells a suspected perp a pack of lies in order to get them to make a mistake.
One common ploy is to have detectives telling suspects that they have been identified by victims or collaborators. Another is when two perps are involved, separating them and telling each the other one caved.
Unlike many interrogation tropes, this sort of thing has been known to happen quite often in real life and is completely legal in most jurisdictions. Within reason. The official term is "reasonable deception," with the idea behind reasonable being that no innocent person (in theory) would ever fall for it, having not committed the crime in question. Police are usually limited to making false verbal assertions regarding evidence (they can't forge lab reports or witness statements, but they can tell a suspect they pulled his DNA or fingerprints from a crime scene, or that another witness ID'd them). They're generally not allowed to make definite promises regarding plea agreements or mental treatment, nor are they allowed to grossly misrepresent legal principles in order to force a confession.
However, there's a movement to make it illegal, or at least put much harsher restrictions on it. The problem is, it turns out, the standard of "reasonable deception" traditionally applied isn't as obvious as it seems. Relatively recent psychological research has shown this technique has a disturbing tendency to make the suspect confess to things they didn't actually do
Frequently results in I Never Said It Was Poison
. This is one situation where the perp would usually be smart to have a lawyer around to remind him "Don't Answer That
open/close all folders
Anime & Manga
- In Death Note, this is tried several times on the quite-guilty Light by the person investigating him. Notably, the time when Light uses the built-in amnesiac loophole and turns himself in for observation; he's continually told the murders have stopped, even after they've started again. Later, Light's own father informs him he's about to be executed and pretends to shoot him in the face in an attempt to see whether he or Misa would use their powers to kill him.
- L is pretty much constantly lying to Light regarding how much suspicion he is under.
- And Word of God says that L's claim that Light is his first ever friend was a lie.
- To clarify, he hasn't ever had a friend, but Light isn't one.
- Light pulls something like this himself at one point early on. In an attempt to convince them to go along with him, Light tells one character that he has kidnapped "her." While Light is bluffing and has no idea who "she" is, the character still gives in.
- In the manga, Near tells Light that Mogi had died after escaping the mob outside SPK headquarters.
- Although in that case, Near knows that the lie won't fool Light for any length of time. The lie is for the benefit of the other members of the task force, to get them to suspect Light.
- Captain Smoker uses this on Mr. 11 in One Piece, in order to confirm his theory that there's a criminal organization using numbers as code names running around.
- Also after the Time Skip, the crazed Captain Caribou kills a Marine for lying to him that he didn't contact HQ, then stated that the Marines should remove their unwritten rule "it's ok to lie to criminals".
- Inverted in Fullmetal Alchemist when Warrant Officer Falman interrogates Barry the Chopper by checking his memory of his crimes to see if he really is what he claims to be: the infamous criminal's soul bound to a suit of armor. Among the crime examples he uses, Falman changes the date of one of them, and Barry calls him on it.
- The "Truth Crocodile" in Rozen Maiden.
- A variation occurs in the comedy movie My Fellow Americans: a character, tied and blindfolded, is made to think that his interrogators are going to torture him, beginning with truth serum. One of them gets a needle from a sewing kit, goes through the motions of preparing a shot, and just barely touches the crook's arm with the needle when he shouts "I'll talk!"
- Used in A Few Good Men. With Jessup on the stand, Kaffee starts talking about a flight from Guantanamo that (he knows, but can't otherwise prove) Jessup has scrubbed from the records, then indicates two Air Force ground crew, who'd been working at the base the day in question, he intends to call to the stand. Jessup is visibly shaken, and later proceeds to the famous meltdown. Confronted by Ross after the trial ends, Kaffee admits that the two men would have testified they hadn't the foggiest memory if there had been a flight that day.
- Lampshaded in Four Brothers, where the brothers go over their game plan for being interrogated and mention the convenient "hair sample" the cops always use to try and scare a confession out of them. Some of them even laugh when the interrogator pulls out the little baggie and waves it at them.
- The General's Daughter: When questioning a suspect in the gang-rape, Sunhill pulls out a pair of women's underwear in an evidence bag and leads him to believe that they're Captain Campbell's DNA-evidence-filled underwear from the night of the gang-rape. He promptly starts talking about how he tried to stop the rape, and reveals the identities of the other men involved.
- In The Girl Who Played With Fire, Dan, a new reporter at the Millennium magazine, wants to interview a policeman about the sexual trafficking he participated in (as a customer), but the man is understandably evasive. Blomkvist instructs Dan to mail the perp a new phone and tell him he's won a lottery and is legible for bigger prizes if he agrees to participate in a "survey". The guy takes the bait, hook, line and sinker.
- In Zero Dark Thirty this is what finally breaks the suspect and gets him to talk, where hours of Cold-Blooded Torture does not. The captured prisoner is denied sleep for a long time, then offered a friendly meal with his captors; in contrast to the thuggish CIA torturers, Maya establishes her credentials as a savvy and manipulative agent by lying to the suspect that the information he'd given was instrumental to stopping an attack, and congratulates him for helping to save lives. In reality, the suspect had done no such thing—but he was so exhausted that he couldn't tell, and begins cooperating with the Americans from then on.
- Very, VERY common in folktales. One example: each suspect is given a "magical" stick that will, if its owner is guilty, grow two inches overnight. The thief, of course, cuts two inches off his stick and is caught.
- Another example is in "The Tablecloth", in which two women each claim that an embroidered tablecloth which has blown off a clothesline belongs to her. The man who found it announces that there is a wine stain on it. One woman tells an elaborate story explaining how the stain happened. The other woman says, "It must not be mine. Mine had no such stain." Of course, the tablecloth wasn't stained, proving the second woman was the owner.
- Even the venerable Lt. Columbo isn't immune to it. Upon finding that his victim wore contact lenses, he mentions that the right one is missing, and probably fell where she died. The perp breaks into the garage where his car is being held, searches it madly, and finds the missing contact, only to be surprised by Lt. Columbo and the victim's husband. Caught, the perp admits to the murder. Later, the husband notes it's luck that one of his wife's contacts fell out this way. Columbo replies that the corpse still has both its contact lenses; he lied to the perp and has no idea where that lens in the car came from.
- In both Homicide: Life on the Street and The Wire, a photocopier pre-loaded with sheets of paper marked "TRUE" and "FALSE" was passed off to a perp as a new, highly accurate, highly dangerous lie detector. Silly as it sounds, the story originates in David Simon's non-fiction book Homicide: A Year on the Killing Streets.
- Homicide again: Detective Bayliss convinces a perp that his special camera can detect the image of the last thing a murder victim had seen by photographing the dead man's eyes.
- One more Homicide example: faced with an unflappable perp, a dog-lover who had used arson to conceal a murder, the detective asks, offhand, "We found a dog in the wreckage. Why'd you kill the dog?", a total fabrication. Without thinking, the perp reflexively answers, "I didn't know the dog was there."
- Where Homicide is concerned, this is a Once an Episode trope if ever there was one.
- David Simon wrote the ol' photocopier-as-lie-detector trick into yet another series, when Bunk uses it in the opening scene of the fifth season of The Wire.
- The first season of The Wire has a particularly egregious example, where the detectives claim that a picture of Bunk's kids are the kids of a murder victim in order to get D'Angelo Barksdale to write a letter saying he's sorry to them. His lawyer arrives in time to snatch it off him, and his the-morons-I-have-to-deal-with demeanor is hilarious.
- The photocopier-as-lie-detector story is actually much older and probably never happened in real life.
- CSI: Crime Scene Investigation: Warrick convinces a suspect that an on-site DNA test has ID'ed him as the perp. Really the test only determines if the substance is human blood.
- Another episode had an interesting variant when Sara and Catherine, without comment, brought in a bag issued to employees of an airline the victim worked for. "Well?" Sara asks. The suspect, talking over his lawyer's attempted warnings, then tried to point out that the bag was inadmissible because they didn't have a warrant to search his car. Then Sara informed him that the bag didn't belong to the victim but did contain a recording device.
- Subverted when Warrick is the one being interrogated for the murder of mob boss Lou Gedda. The detective tries to goad Warrick into a confession, spinning a wild story of revenge and justice, telling him they have evidence that he did it, and even bringing up Warrick's guilt over the death of Holly Gribbs (from the pilot episode). At the end, Warrick calmly looks up at the cop and tells him he's going to have to "step up his game" to get him to crack.
- In the Law And Order: Special Victims Unit episode "Legacy," Munch tells a victim's mother that her comatose daughter has awakened and "told us everything." After the mother confesses, we find out the little girl is still in a coma.
- Another SVU example: Captain Cragen tells a perpetrator that they used DNA analysis to prove that the cigarettes he smoked were used to burn an old woman. When he goes back behind the two-way mirror, Detective Tutuola reminds him that the lab found all DNA from the lit end of the cigarette to be burned away.
- This one is used in Criminal Intent (the first episode, even): Goren convinces the girlfriend of a narcissist perp to help them by convincing her that he gave her AIDS. At the end, when he finds out she betrayed him, she shouted "You killed us both anyway!" to which Eames reveals that neither of them had AIDS after all, to which Goren half-heartedly admits, "I lied. Sorry."
- There was also at least one where they lied not only to the perp, but to the ADA. "Ah...I see," he responds, clearly pissed.
- In another episode, Goren convinces a man that his wife (whom he put into a permanent vegetative state and is now trying to take off life support to collect her life insurance) is able to communicate by looking at "yes" and "no" cards. It's actually just involuntary eye movements.
- There was also another one where the detectives had the ADA get a warrant for a suspect's garage, saying that there was a tooth cap that was left in there and would prove the suspect killed the victim, which will be delivered the next morning. The man stays up all night going through every inch of his garage, even down the drain, to make sure he didn't miss what the cops were looking for. When they arrive, he's rolling on the floor, dazed from a lack of sleep and paranoia, laughing that he did the murder perfectly and didn't leave a trace of evidence in his garage. This ends up being what the cops wanted, since they knew what they were looking for wasn't there.
- Actually they didn't even have to lie in that one; they just asked the guy's wife if she'd found a tooth in their home. They knew she would tell her husband, and that he was such a perfectionist he'd go nuts looking for it.
- Original flavor had a similar plot, when McCoy put a comatose girl on the witness list for the trial of her attacker. He also told the doctor that when the perp's lawyer called, he was to say she was awake and talking to police. The doctor agreed to, under protest, and the defense pleads out without checking in person.
- Goren once got a confession by telling the suspect that he hadn't actually committed any crime (of course, by the time his admission was done, he was guilty of some criminal negligence for allowing a patient under his care to die). Police are in fact not allowed to tell a suspect they're not guilty of a crime.
- Subverted in mothership episode "Ritual." Detectives suspect a man of committing murder in a parking garage and then driving out of it, using his magnetic key-card to exit the garage. However, the garage's gate system doesn't record card usages, and with no witnesses they have no way of knowing whether he did actually use his key-card that evening. They decide to bluff and tell him in interrogation, "We checked the readout at the garage. Your card was used just after Uncle Josef got his head bashed in." As they say this, the suspect lights up with a smile and faint glimmer in his eyes. "The magnetic card system?" he calmly replies; "You can't get a readout from that thing." D'oh!
- This actually happens a fair few times on various incarnations of "Law & Order". Considering the sheer number of episodes the show has, a Genre Savvy perp makes things interesting.
- An important distinction is also made in another episode of the mothership when Jamie Ross plays a clever game of half-truths to convince a perp to surrender the gun he used to kill a woman. Though she's able to convince the judge to allow the gun into evidence anyway, he makes it clear that while he accepts the idea that cops can lie to suspects, he expects more of an ADA.
- Similarly on One Life to Live. Rookie cop Andy has been arrested on charges of corruption, thanks to being framed by the cop who was actually guilty. Also arrested is a local hoodlum who has been trying to help her in her investigation of the crooked cop. When the police commissioner interrogates the hood, he tells him "Andy already told me everything, so we just need your statement, etc." However, having been in and out of the system, the guy is fully aware of the tricks that cops use and doesn't believe him for a second. Not to mention the fact that he knows full well that he and Andy are innocent and that Andy, being a cop herself, isn't likely to fall for the police tactics either.
- An early CSI: New York episode has a victim whose head was slammed into a restaurant oven; the victim staggered out of the restaurant and collapsed on the street. During the interrogation, the suspect is told "then you followed him out and shot him dead." The suspect immediately admits to the head-slam but not the gunshot, only to discover the victim died of the head trauma and was never shot.
- In many series, police officers will claim that the suspect's colleague has claimed that the suspect did it, or is about to break down, and will offer the suspect leniency if he just admits that it's his fault. This only rarely works. Probably based on the classic Prisoner's Dilemma
- In The Shield episode "Blood and Water", Det. Vic Mackey (who is blue eyed, with head shaved) pretends to be a neo-Nazi to get a suspect to open up (it doesn't work).
- Det. Wyms and Wagenbach use this tactic all the time. Most notably, Wyms baits a confession out of a serial killer by telling him that his sister had been murdered in the same fashion as his other victims. After he confesses, she points out the sister waiting in the office below. This comes back to bite her when he discovers that Wyms was on medication that she had concealed from the LAPD at the time, scaring the DA enough that she dropped the death penalty.
- Though not itself a Crime Fiction, the Star Trek: The Next Generation episode "The Drumhead" had an interrogator use this tactic on a young medical bay Lieutenant. A Klingon spying for the Romulans was discovered early in the program shortly after an explosion rocked the Enterprise's warp core, seemingly committed by sabotage. The explosion was later discovered to be caused by a faulty seal, but convinced of the Lieutenant's guilt by association to the spy, and the fact that his grandfather is Romulan, the interrogator attempts to force a confession out of him by claiming that evidence was found of a corrosive chemical causing the explosion, which the Lieutenant had access to. Subverted when the Lieutenant (rightfully) rebuffs the accusation, and Picard later chides the interrogator for using the tactic as unjustified and uncalled-for. In this case, the unethical interrogator had even opened up the previously private interviews to a public audience; presumably, so that the false accusation would apply even more pressure by destroying the young officer's reputation whether it was true or not. Picard is then hauled before the interrogator himself for questioning its methods, where he gives her a well-deserved "The Reason You Suck" Speech, pointing out the similarities with numerous other unfair legal processes in the past.
- When Worf's family is accused of treason by the Klingon High Council, Picard — suspecting the accusation is a cover-up — calls a woman who served Worf's family as witness, falsely claiming that she has new evidence. The bluff reveals the real traitor, though the High Council is too compromised to drop the charges and Worf is banished from Klingon society.
- There is a scene from the short-lived Denis Leary show The Job where the detectives in question lie to a suspect's mother, telling her that he is dead, to make her cry, while two other detectives tell the man that the others are beating his mother. It works, and he's only too happy to talk.
- NYPD Blue: Two lies used frequently were: A) A vehicle was involved in an accident and your license plate number was reported, it's probably just a mix-up but we have to do the paperwork; B) [Victim having died without identifying anyone] 1. The victim is talking and has identified you so it'll go easier if you confess, 2. You should write out a confession telling your side of the story, 3. The victim is dead, you're going away for murder based on your confession, you SOB.
- In one case the detectives convince a suspect to take part in a lineup by telling him that he'll be a ringer and that the lineup is for an unrelated crime. Criminals have been caught this way IRL, both on purpose and by accident.
- Happens all the time on Criminal Minds. One particularly memorable episode involved Jason Gideon helpfully providing prayer time/rugs/etc. for an imprisoned Muslim fellow, but really he was just manipulating the guy's sense of time.
- Another time, a character convinced a serial killer who was holding him at gunpoint not to kill him right away by claiming "I know why you stutter". Not only did the investigator not know why this particular man stuttered, but nobody knows why stuttering occurs (though there are theories).
- There's also the absolutely brilliant climax of "Masterpiece". Rossi tricks an arrogant Unsub into thinking that he's killed the entire team (save Garcia and Rossi himself) through a trap in his house. Believing that there's no evidence to convict him, he confesses all the details... and Rossi asks Garcia "Did you get all that?" Turns out, the team is very much alive, having figured out the trap long beforehand. As Rossi himself points out, he teaches hostage negotiation at Quantico.
- In "Profiler, Profiled", Morgan believes that the cops accusing him of murder are using this trick when they were interviewing him, even saying "We (FBI) invented this!"
- Also notable for using this to rule out false confessors.
Gideon: Is that why you stabbed him in the groin?"
Suspect: It's what he deserved!
(The victim had, in fact, been stabbed in the head).
happens all the time Once an Episode (if not more) on The Closer. Perhaps the ultimate example was when Deputy Chief Brenda Johnson told the perp that she was the public defender assigned to him.
- Having just finished a semester of Criminal Procedure at law school, one can say that lying to suspects is not just a trope but often Truth in Television; this, however, would be a violation of the suspect's Constitutional right to counsel, making this a case of failing Constitutional Law forever (and probably getting any evidence obtained from the discussion thrown out of court in Real Life.)
- She apparently didn't say she was his public defender, she just implied it and let him jump to that conclusion. She does introduce herself as being from the Public Defender's office, but those watching the interview also note that in this case the deception is only fine as long as the witness doesn't say anything they have to prosecute him for.
- Brenda not only lies to get the perp to confess, but pretty regularly lies to get them to waive their Fifth Amendment rights. Hopefully that wouldn't fly in the real world. Unfortunately, if you're talking, by definition you've waived your Fifth Amendment rights.
- Pope sums this up pretty amusingly in one episode. Brenda's lawyer, who is watching her in an interview, ask if she is lying to the perp. Pope immediately replies, "How long have you known her? Of course she's lying."
- In an episode of Mash Hawkeye is wrongly accused of stealing. So he gathers the alternative suspects together in one tent (while dressed up as Sherlock Holmes) and says one of the stolen items was a trap — it had been coated in a chemical that turns the hands blue. When the guilty party instinctively hides his hands, Hawkeye points out that he was actually bluffing.
- In one episode of Shark, the title character attempts to coax a confession out of a perp by claiming that someone will testify against him unless he signs a confession. The problem is that the supposed person is dead and the lie falls through immediately when the man's lawyer notices how quickly Stark is pushing for him to sign it. Stark almost ends up losing his license to practice law as a result.
- Dr. Cal Lightman in Lie to Me does it about Once an Episode.
- QI described an Elizabethan mathematician, John Napier, who "encouraged his servants to stroke his cock" - one of them had been stealing, and he got them all together and told them his pet cockerel could tell when someone who touched it was lying. He sent them into a dark room and told them to stroke it, while unbeknownst to them it was covered in soot - the guilty servant was the only one not to have soot on his hands.
- Done in Jonathan Creek, when Maddy tells the suspect she's been incriminated by skin cells left in Jonathan's shoulders when she gave him a massage, and once she gets a full confession:
- Castle does the "divide and conquer" ploy in "The Double Down" to break the beta of the "Strangers on a Train"-Plot Murder pair.
- Non- Crime Fiction example: In Three's Company, Janet exposes a crooked health inspector who demanded a bribe in order to keep Jacks' perfectly acceptable restaurant open:
Janet: When are you going to own up to the $500 you demanded from him?
Inspector: It was only $126.
- On Without a Trace this came back to bite Elena's old partner: she told a murderous drug dealer that a neighborhood woman saw him kill one of his rivals. The dealer never cracked and instead put out a hit on the woman from jail and was never charged with either murder.
- In a Babylon 5 episode, psychic Magnificent Bastard Bester is allowed on board the station only if he agrees to take telepathy-blocking drugs. He then sits in on an important interrogation. After spending a while looking bored, he blurts out, "He's lying." The perp immediately confesses everything. Garibaldi suspects that the blocking drugs have failed, but they haven't; Bester was just bluffing. His reputation and uniform were enough to make the perp break down.
Liars are always afraid that somebody's going to see through them. So I just provided him with a vehicle for his paranoia. Your captain's opinions notwithstanding, the badge and the uniform do have certain ... advantages. Garibaldi:
Like intimidation? Bester:
Absolutely! Just like... your badge, and... your uniform.
- In one Bones episode, they told the killer that they'd charged someone else with the murder. He was so vain that he confessed just to get the credit.
- In one episode of Neighbours, a man arrested for assaulting Chris names Jarrod as the man who paid him to. Jarrod effortlessly exposes him as a liar by showing up at the interview with Superintendent Hayes and leading Walton to believe he is his Legal Aid lawyer. By the following scene he has changed his story.
- Played for laughs on The Golden Girls. One of the Empty Nest characters, Barbara, had crossed over for the episode and had to help the girls when a guy came into the house with a gun.
Rose: You said you didn't have a gun, you lied!
Barbara: To a bad guy. It's okay to lie to a bad guy.
- An undercover cop pulling a buy-and-bust on Breaking Bad rouses Badger's suspicions, but he covers himself by saying "If you ask a cop straight-up if he's a cop, they have to say yes. It's like, a law or something." He's asked, he denies it solemnly with his hand to God, and they complete the deal. "You have the right to remain silent..."
- Can be used in the party game Werewolf. In one case, Player A claimed to be the seer and accused Player B of being a werewolf, hounding him sufficiently to extract a confession. Player A then confessed that he had no evidence of Player B being a wolf in the first place.
- Humorously deconstructed in The Accidental Death of an Anarchist.
- In Doubt, Sister Aloysius claims she spoke with some nuns at Father Flynn's last church when confronting him about his relationship with Donald. She later admits to Sister James that she did no such thing.
- One case in Phoenix Wright: Ace Attorney was ended successfully by Phoenix's use of such a lie (confusing the color of a poison vial) to confess (by way of correcting the color, implying that he would have to have done it to know what the real color was).
Phoenix: This bottle has your fingerprints all over it! And it contains... potassium cyanide!
Suspect: HA! You'll need to do better than that! The cyanide was in a brown bottle! Not a green one!
Phoenix: Oh? How did you know that?
- And another involved an extremely subtle lie. 'Adrian Andrews' is a pretty masculine name, so Wright leads Shelly De Killer on by letting Shelly lie about his meeting with Adrian. He uses male pronouns, so Shelly uses them too...and then Wright accuses him of lying about having ever met Adrian in the first place. Adrian is a woman.
- Early on in Suikoden I, Odessa uses this to confirm that the pick-up man for a vital blueprint she needed delivered was the real deal (he is).
Kage: My name is Kage. I have been sent by Sir Mose, chief of the secret factory.
Odessa: Mose certainly keeps unusual company. How is he? I received a letter from him mentioning that a pigeon of his was sick. I find it hard to imagine Mose taking care of a sick pigeon.
Kage: Very strange, lady. Sir Mose does not keep any pigeons.
- You can pull one on a robber in Fallout: New Vegas if your perception is high enough. The girl has just taken a necklace made from rare Sunset Star Sarsaparilla caps off the guy she killed "in defense", and claims that it's hers. You claim that you've never seen bottlecaps like "those six", and she agrees that they're very special. You then point out that there are actually seven caps, which she'd know if she really owned it in the first place.
- An amusing example in in Skyrim: One of the in-game books tells of a prince who throws a lavish dinner for several of his advisers. After dinner, he brings out a dessert and explains that some of the advisers are spies and were poisoned during the dinner (it's strongly hinted that all the advisers present are spies). He then says that the dessert contains the antidote. This presents a conundrum to the attendees - eat the dessert and essentially confess to being a spy, or refrain and possibly die from poison? One of them finally decides to eat... and dies rather horribly from the poison in the dessert.
- A tactic occasionally used by real police is to mail hundreds of people with outstanding warrants letters saying that they had won a prize, but must present themselves in person at a specific place and time to claim it. Such stings often result in dozens of arrests.
- The film Bernie (which was based on a true story) has the DA do something like this. He organizes a fake contest in which the person who kept their hand on a new car the longest would win the car, using this to lure out men who owed child support so they could be arrested.
- Real Life example. In several of his books, John Douglas goes into detail about some of the more creative techniques for perp sweating and obtaining confessions. He ends by explaining that, were he on the receiving end, he'd take whatever deal was offered. It's honestly in your best interests to do so, as lying and drawing the process out only makes things worse for all concerned.
- Except that the police aren't the ones who cut deals, prosecutors are, and any "deal" made with the police is null and void. Oops. Increasingly in fiction, the police merely say they talk to the DA with cooperation.
- As your lawyer should tell you if present. If he's not, why are you talking at all? (at least in the US.)
- Cops strongly (and correctly) suspected that Susan Smith was lying about her children being abducted by a carjacker. So they told her that the police had been staking out the intersection in question (where she told them the abduction had happened) and knew for a fact that no such incident had taken place. Their strategy worked—she confessed.
- One very disturbing result of this tactic is that it can also convince innocent people to confess and/or plead guilty because they don't see any hope of winning in court. Even more disturbing in the case of 14-year-old Michael Crowe. The police told him they had physical evidence that he had murdered his sister. Even though he was innocent, he not only confessed, for a while he actually came to believe that he must have done it.
- According to David Simon in Homicide, this is basically a requirement of being a detective. A good detective must be able to read a suspect his Miranda rights, (and in Baltimore) sign a paper showing they've understood them, and then in the very next breath convince the suspect that those rights are meaningless. From there, it's half-truths and lies all the way. For example: One common trick is to confiscate the suspect's shoes and tell the suspect that they're going to check that blood splatter on them to see if it's the victim's blood type. It serves a double-whammy: The suspect is convinced they have evidence, and their faith in themselves is shot; hell, they didn't even notice that any blood splatter had hit their shoes!
- Simon also notes other things of even more dubious legality, such as using a Xerox copier as a lie detector. The detectives load three sheets of paper, reading "truth", "truth", "lie" into the machine. The questions are answered, and "copy" pressed. What is your name? "Alice" Truth. Where do you live? "Troperville". Truth. Did you kill Bob on the night of the 25th? "No". Lie. Well well well. You lying motherfucker. Confession. Another detective uses the sobriety test ("look at my finger, cross your eyes, stand on one leg"), telling a perp it is a kind of ninja truth technique. This works. Another extremely stupid suspect admits to beating a woman into unconsciousness, robbing her, and orally raping her, but is convinced by a detective's assurance that, because he didn't actually strike the mortal blow, he cannot be charged. As one detective notes: "Ignorant motherfucker."
- According to QI, Elizabethan mathematician John Napier suspected his servants of stealing from him. He sent them into a darkened room one after the other, telling them to place their hands on a pet rooster he claimed was a Living Lie Detector and confess their innocence. The bird had soot on it, so anyone who came out with clean hands must be guilty.