Luigi: It's a me, Luigi! Mario was my brother! I can't believe he is gone!
While discussing about the brewing conflict between the Italian and Irish communities of Crimson Banks, Isaac and the player are informed by Chief Wright that the body of "Papa" Mario Fortuna, a community pillar and revered face in Crimson Banks, has been found at the district's marketplace, dead after being strangled with a flag garland.
Tropes:
- Absurdly Spacious Sewer: One of the crime scenes is a sewer where the Irish gang has been storing weapons to use against the Italians in an oncoming attack.
- Always Someone Better: Kieran saw Papa Mario as this, since both of them were pillars of the community that helped the people of Crimson Banks however they could, but Mario received all the praise while Kieran was left in the dust. It's the reason why Kieran decided to kill him.
- An Immigrant's Tale: Mario and his brother Luigi arrived to Concordia from Italy and managed to become well-known faces among Crimson Banks, as Luigi opened a famous delicatessen while Mario became a community pillar who always looked afters his fellow citizens.
- Astonishingly Appropriate Interruption: How Viola appears to inform you that the flyer you found comes from William Shakespeare's Othello.Evie: For once I didn't have to search high and low to find information about that flyer. Viola says-Viola: It's a quote from one of my favorite plays!
- Call-Back: Mayor Cornelius Castletown reappears as a suspect after being absent since Case 19. Adrienna Brassiere also reappears during the Additional Investigation.
- Choosing Neutrality: Bridget's stance regarding the brewing Mob War between the Irish and the Italians amounts to this.Bridget: I know to steer clear of gangsters... I'm just a grubby old sewer rat fixing pipes!
- Cliffhanger: The case ends with Evie informing you that Commissioner Talmadge Baldwin has been found dead at the docks.
- Continuity Nod:
- Archie Rochester being Mr. Alastor is brought up again when you meet his mother.
- When you flag Veronica Rochester as a suspect, Isaac mentions how you she's the first Rochester you've found since the World Exhibition.
- Viola's peanut allergy is brought up when Charlie asks her to test his DNA machine on her father to see if they share it.
- Corrupt Corporate Executive: Although not entirely proven, Mario accused Veronica Rochester, who is the owner of an alcohol company, of selling whiskey in the middle of a prohibition.
- Dead Guy on Display: During his trial, Kieran admits he left Mario's body in the marketplace so everyone would see what a "pathetic weak man" he was.
- The Food Poisoning Incident: One of the killer's traits is that they're suffering from food poisoning since they puked over the murder weapon. Bridget and Kieran even accuse Luigi's delicatessen of giving them spoiled food.
- Good Samaritan: Mario is described as being a community pillar who has dedicated most of his life at helping Crimson Banks and its inhabitants grow, and was even part of the City Council along the likes of Mayor Castletown. Unfortunately, this didn't stop him from gathering a few enemies, with one of them being his killer.
- Green Around the Gills: Since one of the killer's traits is that they're suffering from food poisoning, some of your suspects turn green during your interrogations with them. The same happens to Isaac when you visit the sewers as part of the investigation.
- Green-Eyed Monster: Kieran Quinlan murdered Mario because he was jealous of Mario receiving all the attention in Crimson Banks while Kieran had also been helping the community but no one acknowledged him.
- Great Escape: During the Additional Investigation, you're informed that Seamus O'Neill has escaped from prison, and you also later find out that it was the Irish gang who broke him out, intending to make him their new leader due to killing Vittorio.
- Improvised Weapon: The murder weapon is a flag garland, something that Dick also finds strange.Dick: You mean apart from the fact he was strangled with that flag garland? An unconventional murder weapon, I must say.
- Intellectual Animal: Ratsputin, Rose's pet rat, manages to find a crate full of weapons inside of the sewers below Crimson Banks, giving you more leads about the murder and the Irish-Italian conflict of the district.
- Not-So-Omniscient Council of Bickering: Despite being together in the City Council, Mayor Castletown confesses that Mario was trying to force him to quit being the mayor of Concordia, as Mario was convinced Castletown had rigged the votes.
- Peace Conference: Kieran lured Mario to Luigi's delicatessen with this excuse, claiming that he wanted to make a peace deal between the Irish and the Italians to prevent the Mob War from escalating. However, this was only a trap set up by Kieran to murder Mario.
- Prone to Tears: Luigi Fortuna, Mario's brother, is seen crying whenever you interrogate him.
- Shout-Out:
- The case's title comes from the Romeo and Juliet quote, "Where civil blood makes civil hands unclean."
- The case contains a handful of references to Super Mario Bros.:
- The victim, Mario Fortuna, is Italian, plump, has a thick mustache, has a penchant for wearing red, and is considered a celebrity among the community.
- Luigi, Mario's brother, is thinner, has a smaller mustache, wears green, is Prone to Tears, and is less famous than Mario, as he only runs a delicatessen.
- Bridget Baker, who is blonde and has blue eyes like Peach, works as a plumber, which is the Mario Bros' occupation in the series.
- Chapter 2's cover image (pictured above) features a picture of the Fortuna brothers besides jars of mushrooms and "Star Noodles", and Chapter 3's cover image features Bridget climbing out of a pipe.
- William Shakespeare's Julius Caesar, As You Like It, and Othello are mentioned.
- Sibling Rivalry: Luigi had grown to resent Mario because he wanted to demolish Luigi's delicatessen to build a casino to make the community grow, and even declares Mario was cunning and manipulative below his noble exterior.
- Stealing from Thieves: Bridget stole a few bullets the Irish gang hid in the sewers to sell them for some money, as plumbing doesn't pay that much.
- Understatement: When you interrogate Veronica, she brushes off Archie's actions as Mr. Alastor and calls it "a misbehavior".
- Unpleasant Parent Reveal: During the Additional Investigation, Charlie runs a test on a glove pertaining to Viola's father to see if her peanut allergy comes from him, only to discover that Viola and her supposed father aren't actually related. Needless to say, Viola doesn't take this well.
- Vote Early, Vote Often: Mario accused Mayor Castletown of rigging the election and winning his second term unfairly, and even attempted to make him resign, giving Mayor Castletown a reason to kill him.
- You Are in Command Now: During the Additional Investigation, you discover from Adrienna that the Irish gang broke out Seamus from prison to make him their new leader, as murdering Vittorio, the Italians' leader, made him the perfect choice for them.
