We could fill the trope page entirely with Law & Order examples. It's pretty much S.O.P. for L&O shows: if the feature guest star isn't the defense attorney, the victim, or the first suspect, he's the perp.
- On Law & Order: Criminal Intent, though, it's often obvious who the killer is right from the start as the show is about how the detectives will catch them, rather than whodunnit. It's now being lampshaded in the Law and Order promos.
- In earlier episodes like "One" and "Jones" and later ones like "Major Case" and "Family Values" we know the killer from the teaser, but usually we don't.
- In an episode of Law And Order: Criminal Intent, Stephen Colbert plays a graphologist hired to authenticate some documents, only to find out that he forged them, and committed the original murder. This was before Colbert's show began, but he was already well-known as a reporter on The Daily Show and for Strangers with Candy.
- One episode of Special Victims Unit managed to avoid this by having three well-known guest stars (Bob Saget, Chris Sarandon and Catherine Bell) so it wasn't immediately obvious who the killer was.
- Yep... another Law & Order: Criminal Intent entry. They interview the woman who ran the prime suspect's foster home, Whoopi Goldberg (with short hair, no less). Guess who's behind the whole thing?
- A well-done example is "Pure", the episode of Law & Order: Special Victims Unit featuring Martin Short. It's never in question that he's the guilty party, and the entire episode is a battle of wits between Short and the detectives as he taunts them to prove it.
- A similar SVU example, the episode "Uncle", involved guest star Jerry Lewis. Producers must've been particularly aware of the trope this time as even the promos gave away that he did it, and indeed the crime ultimately committed by his character was done right in front of the eyes of the star detectives — the episode's plot revolved instead around tension leading up to the crime, whether or not he was justified in his actions and whether or not mental incompetence played a role.
- Just plain averted in the episode "Trade" with guest stars Matthew Davis and Stephen Collins. Neither one of them did it.
- Averted in an original flavor Law & Order episode, in which Kevin Smith appears — in a one-scene cameo.
- In "An Evening With Kevin Smith 2", he says that he wanted to play "the guy who leads them to the guy, who leads them to the guy, who leads them to the guy that did it". And he did.
- Also averted in an episode of SVU in which Karen Allen is the murderer's wife ("Scourge"), but played straight in an earlier episode of the original Law & Order in which Allen is the killer.
- In a SVU episode, Eric McCormack played the killer's father. He confesses and everything!
- One SVU episode, "Design", in quick succession, had the detectives talking to Bobby Flay, Mark McGrath, and Jesse Palmer, all playing Expies of themselves, about halfway through the episode. However, they are all past victims of a malicious female rapist that had not reported it for some reason. While the actual rapist was played by the relatively unknown actress and Olympic bronze medalist, Estella Warren, her accomplice and mother, was played by none other than Wonder Woman herself Lynda Carter.
- Subverted: One episode of Law & Order: Criminal Intent featured Brent Spiner, a.k.a Lt. Cdr. Data, and Margaret Colin (who co-starred with Spiner in Independence Day) as one half of a pair of married psychologists. They were both arrogant twits, but neither of them was the killer.
- Another subversion: One Law And Order: Criminal Intent episode featured Judd Hirsch and Anthony Mackie (before he became really famous). Neither character was an angel (Mackie's character is based on Jayson Blair) but neither was a murderer.
- An inversion: One episode of SVU in which the guest star was Lewis Black as a Howard Stern-like radio DJ. He was never a suspect, but later in the episode, he gets shot in the shoulder by the culprit's mother. The jury acquits.
- Not entirely, as Ricky Ullman, Maggie Grace and Dana Delany were also present as Perp, Victim and Shooter of Lewis Black respectively. It was basically Ullman's "Look at me, I'm not chained to Disney, I have range" casting reel.
- The next to last episode of the 11th season of SVU has an interesting example: While the perp is known from early in the episode, his father shows up late in the episode and is played by Raymond J. Barry, who's seemingly too ubiquitous to JUST be the perp's dad. Not surprisingly, the father was abusive and conspiring with his son.
- Malcolm McDowell deserves to be far more than the average perp when he appears on CI, and indeed, not only is a Chessmaster par excellence, he gets away with his crime in the end.
- Another Criminal Intent subversion: Rip Torn guest starred in one episode as a rather cold, unfeeling, and downright unpleasant multi-millionaire who, despite being mean (and despite being portrayed by the big-name guest star), wasn't involved with the murder.
- And another: John Glover not only got to be creepy and suspicious in his appearance as Goren's forensic psychology mentor, he also got to be completely innocent. At least the first time he was on.
- And another: Terry O'Quinn guest-starred as Gordon Buchanan, the senior vice president at a pharmaceutical company which sold a batch of HIV-infected blood incorrectly labeled as synthetic plasma. The executive responsible is murdered at the beginning of the episode, but not by Buchanan, who didn't even know about the contamination.
- A semi-subversion in a 2010 SVU had 4 famous (from 25+ years ago) guest stars: Ann-Margaret, Jaclyn Smith, Morgan Fairchild and Susan Anton. Only one of them did it. And in the show, she's no angel.
- Yet another Criminal Intent episode; it featured Dylan Baker, normally a character actor as he's been in everything
, including three different characters in the mothership show. However, the previews for the episode pointed out that Dylan Baker would be guest starring, somewhat unusual for a character actor to be promoted this way. And yes, he did it. - Double Subverted in another 2010 SVU episode, where Henry Ian Cusick is not only cleared early in the episode but doesn't even appear again...until the next episode, in which he is the culprit.
- Subverted in the SVU episode "Wet", which had David Krumholtznote as an Absent-Minded Professor who grow poisonous mushrooms and was obsessed with water right seemed like a slam dunk as a perp. Plus it also had Rosemary Harris (who played Aunt May in the Spider-Man Trilogy movies) as a Rich Bitch who ran the charity where the victim was given the poisoned mushrooms. Add to that the special guest ADA for the episode was played by Paula Patton from Precious and the defense attorney was played by Michael Boatman from Spin City. Yet none of them was the kill, however, one of them came off as worse than the actual murderess, and was responsible for her behavior.
- The SVU episode "Mask", which has Jeremy Irons as a sex addict turned psychologist who specializes in treating them... turns out to be a good guy who helps the main characters after some plot dithering, and also turns out to have NOT committed the terrible crime that he thought he had 20 years ago, namely raping his daughter in a combination of alcoholic blackout and irresistible impulse (it turned out to have been her best friend, and it was consensual, but his daughter, a lesbian, was also in love with the girl and never forgave her father for breaking her heart.
- Subverted in the SVU episode "Angels": Arrested Development's Will Arnett plays a guy involved in a child sex tourism ring, but he's not the main perp. He's not even a pedophile, just a trafficker.
- Played with in the Criminal Intent episode "Malignant". Stephen Tobolowski, a character actor who is recognizable enough to qualify for this trope, plays a pharmacist who, it turns out, has absolutely nothing to do with the drug-delivery hijacking/double-murder that opens the episode except peripherally. That said, it turns out that he's scamming his customers by watering down his drugs, thus quadrupling the money he's making on each drug shipment.
- One of the perps arrested for the original crime is played by Paul Wesley, credited as Paul Wasilewski (his birth name).
- Subverted in "Torch." Oh look, Brad Dourif is in this episode. His character? A scientist called in to analyze the crime scene, with no prior connection to the case. And this raises the possibility the fire was really an accident and helps the suspect avoid prosecution.
- In the Criminal Intent episode "Cherry Red," Paul Dooley and Dennis Christopher play father and son for the third time. The detectives suspect Christopher's character, a state public administrator, killed a young woman named Kate Finoff to cover up his murder of an elderly woman whose assets he stole. Turns out he only killed the elderly woman; his dad killed Kate Finoff to cover up his son's crime because he, a "sick man," didn't want to be left alone with nobody to take care of him.
- Played with in SVU season 12 episode "Disabled." Singer/actress Jill Scott plays the sister of a quadriplegic rape victim. While Scott's character had nothing to do with the rape, it was discovered that she was physically abusing her sister.
- Subverted in another SVU episode, "Father Dearest", where the Serial Rapist/killer is not Eric Close's character, despite of course having been presented as such for the first 2/3 of the episode, but a vengeful former colleague played by James Van Der Beek.
- Played with by "Dominance" in Law & Order: Special Victims Unit. Frank Langella is the father of a suspect...so he did it, right? Nope, it was Ian Somerhalder. Except that this episode aired in 2004, meaning that it would have played as a subversion in 2004, but now is a case of it being "not that recognizable actor, but this one."
- SVU's "Ballerina", Season 10 ep. 16, had Carol Burnett, Matthew Lillard, and Vincent Curatola to choose from as suspects.
- Subverted in SVU's "Padre Sandunguero", Season 16 Episode 12, where Jack Noseworthy, as the uncle of the 15-year-old rape victim, turns out to be a red herring.
