Consulting a Convicted Killer

A Serial Killer (or other dangerous, violent criminal) is on the loose, and the Great Detectives and Profilers running the investigation are desperate to find the perpetrator before he strikes again. But luckily, the police have another serial killer already behind bars, who, through knowledge of his own malfeasance, may help the investigators to get inside the mind of the suspect being pursued.

Desperate for leads and not willing to "become" the person he is looking for, the detective running the investigation will still seek this insight by making, at least, one visit to the jail cell of this special prisoner who is just as demented and evil and dangerous as the maniac currently on the loose. Such a prisoner is typically so dangerous that special precautions (shackles, straight-jackets, etc.) need to be taken either to make sure he can't leave his cell or can't attack the detective visiting him. Nonetheless, this prisoner is the only person who can understand and figure out what the detective's suspect is thinking.

Receiving this insight will usually come at a price, however. In exchange for any help he gives towards catching the killer at large, the prisoner will typically want something in return, including freedom or greater/extended privileges within captivity. Occasionally, the detective paying the visit(s) may be personally responsible for the prisoner being behind bars in the first place, adding to the tension in their meetings. As such, the prisoner may hold ulterior motives for seeking vengeance or escaping captivity or may otherwise try to deceive the detective. However, one way or another, the prisoner will usually be providing some clue as to who the killer on the loose is or where he could be found.

The Trope Maker is Hannibal Lecter from the Red Dragon and The Silence of the Lambs novels, written by Thomas Harris. Trope occurrences frequently pay direct Homage to Anthony Hopkins's portrayal of the character in the film adaptation of Lambs. However, where much of Lecter's insight provided to the FBI in catching serial killers derived from his skill as a brilliant yet twisted psychiatrist, most other characters in this role will generally give insight based on the modus operandi of their own crimes in helping to catch a similar perpetrator, if not a flat out Copycat Killer.

Compare: Recruiting the Criminal, in which such a person is elected to carry out specific tasks at hand for which their devious skills are useful.

Anime and Manga

 * In Pluto, Gesicht is tracking a serial killer who might be a robot, and consults Brau 1589, previously believed to be the only robot who ever killed a human.
 * In Majin Tantei Nougami Neuro, Yako often gets help from one of the killers she helped catch, Aya Asia.

Comic Books

 * In The Long Halloween, Batman visits Calendar Man in his cell at Arkham Asylum to ask him where he might find the killer known as "Holiday". Calendar Man suggests that, the day Batman is paying this visit being a holiday, Holiday is likely looking to commit a murder—specifically, to kill.
 * One brief Judge Dredd Story Arc followed Dredd aiming to catch a spree-killer in Mega-City One who disintegrates his victims' bodies, only leaving their right hands. Noting similarities to a past case involving a spree-killer who had a similar motive with left hands, which Dredd had solved, Dredd consults with the perpetrator of the original crimes, now in an iso-cube. The prisoner requests that he get "a cube with a view" for his assistance, but Dredd convinces him to provide insight unconditionally after threatening him. The prisoner then divulges what he could assume about his Copycat Killer, the most important part being that the suspect must come from Brit-Cit because that's the only place the prisoner's original crimes are given any recognition. Part One of this story arc was even titled, "The Silence of the Limbs".

Fan Works

 * In the Harry Potter no-magic AU Yours, In Murder by radowan, Harry is a psychologist who works with the Mugwumps, an elite police squad that deals with serial killers. Due to a particularly challenging murderer Harry, by the order of his superior officer Albus Dumbledore, has to consult with the convicted serial killer that murdered his own parents, Tom Marvolo Riddle, also known as Lord Voldemort. Of course Voldemort wants something in return and has a load of hidden motives.
 * I'm a Marvel... and I'm a DC's 's "Happy Hour" story arc sees Spider-Man and Batman visit Lex Luthor in custody to ask questions about how his android Lance works, after the Joker had acquired it and began using it for a nefarious purpose. However, Luthor was brainwashed by Joker before the heroes had arrived and informs Joker when they get to him. Luthor only provides helpful information after Batman acquires Wonder Woman's golden lasso, which he promptly uses on Luthor.

Film

 * In Backdraft, Brian McCaffery approaches an imprisoned serial arsonist, Ronald Bartel, when in need of assistance in finding the missing links between a string of recent fires that seem to be connected.
 * In Copycat, Helen and M.J. consult with convicted serial killer Daryll Lee Callum - the same killer who had previously attempted to kill Helen - in order to gain insight into the copycat killer's mind.

Literature

 * As stated above, the Trope Maker is Hannibal Lecter, who fills this role in two novels and, later, feature films.
 * Red Dragon sees Hannibal approached by FBI Special Agent Will Graham, the agent who had originally captured Hannibal, requesting his assistance in capturing a serial killer known as "The Tooth Fairy". Hannibal provides this help to Graham,, in exchange for a first-class meal in his cell and privileges to use the prison library.
 * In The Silence of the Lambs, FBI trainee Clarice Starling visits Hannibal in his cell on multiple occasions for help with catching another serial killer called "Buffalo Bill". Hannibal ends up giving Clarice cryptic clues in exchange for information about Clarice's unhappy childhood.
 * In some versions of King Rhampsinitus and The Thief, the King trying to catch the thief consults an old, imprisoned criminal on how to go about successfully capturing him. Furthermore, some versions of that particular way of telling the story conclude with the older criminal being released from captivity as a reward for his assistance.

Live-Action TV

 * In The Pretender episode "Once in a Blue Moon", Jarod is helping to catch a Copycat Killer, and consults the serial killer who is being copied.
 * In CSI Langston seeks the help of his nemesis, serial killer Nate Haskell, to catch the "Dr. Jekyll Killer".
 * Happened thrice on Criminal Minds:
 * Once when Mad Bomber Adrian Bale was called upon to help stop a copycat bomber and again when a serial hostage taker was asked to help stop a group of copycats..
 * In the second, the guy hired the copycats so the BAU would have to consult with him, which gave him an opportunity to escape.]]
 * Third time's the charm in "Outfoxed", where the team has to consult Karl Arnold when a new family annihilator emerges. When they get in contact with Arnold, they find out that it seems as though the new killer has contacted him.
 * Defied and Deconstructed in a Series 1 episode of Luther when Luther tries to pick Alice Morgan's brain for insight into the killer in one of his cases, she points out that she doesn't suddenly gain the ability to understand other people just because one is a killer like her (allegedly) and that, ultimately, this criminal's mindset is as alien to her as it is to Luther or, indeed, as any human's mindset would be to her.
 * In a fifth season episode of Buffy the Vampire Slayer, Buffy gets Spike to tell his story of how he killed two slayers after Buffy is nearly killed by a normal vampire.
 * The premise of the documentary series Dark Minds pairs a non-fiction crime author and a criminal profiler who revisit unsolved murders believed to be the work of serial killers. They are assisted in their investigations by an anonymous convicted serial killer serving multiple life sentences who offers his own opinion about the potential motivations behind the cases, using his own personal experience to formulate theories.
 * In Lie to Me, Cal ends up turning to a serial rapist and torturer for clues about the recent string of copycat crimes.
 * A situation similar to the above example arises in NCIS, with a serial killer Gibbs put away early in his career.
 * Huntress confronts Clayface with these intentions in Birds of Prey.
 * In Castle, Rick Castle consults with a retired jewel thief named Powell to find a crew of murderous thieves.

Video Games

 * In Fahrenheit, after Carla discovers similarities between Lucas' case and past murders, she visits Janos, the culprit of those past murders, at Bellevue Asylum in order to find out the link both cases.

Web Original

 * There Will Be Brawl re-imagines Kirby as an Expy of Hannibal Lecter, presenting him as an imprisoned cannibalistic serial killer that is consulted in the hope of solving other murders going on.
 * SCP Foundation: SCP-035, a Keter-class SCP, is a cursed mask with a malevolent and sadistic personality; it is highly intelligent and very old, having witnessed many other abnormalities in its history. The Foundation has detained many other SCPs through interviews with it; unfortunately, quite a few interviewers have lost their lives after being seduced and dominated by the foul thing.

Western Animation

 * In The Simpsons episode "The Great Louse Detective", after a failed murder attempt on Homer, the Simpson family approaches Chief Wiggum in order to get help in finding out who would try and kill Homer. Wiggum declares that their case requires "someone who understands the twisted mind of a murderer". They end up seeking Sideshow Bob's assistance, which Bob agrees to under the condition that he have "around-the-clock access to all Simpsons... especially Bart". Because the Springfield PD are useless, Bob effectively takes a more active role in the task at hand and does the majority of the investigative work throughout the episode. Like Bob, the suspect they are after has a revenge-based motive for killing a member of the Simpsons family.
 * The Fillmore! episode "To Mar a Stall" is one big Shout-Out to Silence of the Lambs. In it, Fillmore consults with Randall the Vandal, who is kept in detention permanently, in order to gain insight into the mind of the mystery vandal 'Stainless'.
 * In the Batman: The Animated Series episode "Harlequinade", Batman offers Harley Quinn a pardon in exchange for help finding the Joker, who is threatening to nuke Gotham, literally. Despite questionable loyalty, she actually does.
 * In the Justice League Unlimited episode "This Little Piggy"; after Circe turns Wonder Woman into a pig Batman and Zatanna are brought to the shore of the River Styx to question Medusa, who is currently imprisoned in Tartarus. According to Themis, Medusa was Circe's cellmate, and doesn't like her much, having had to listen to her incessant ranting about gaining revenge on Hippolyta and her ambitions to headline at the Amphitheater for centuries. For her cooperation, Medusa gets 300 years off her sentence, though it's cold comfort for her that she is now slated for release in "only" two more millennia.

Real Life

 * In an attempt to catch the Green River Killer, members of the police task force assigned to the case periodically interviewed Ted Bundy. However, Bundy's advice wasn't very helpful to the investigation (although, in this case, "wasn't very helpful" did not mean "was wrong," and many of Bundy's guesses about the killer turned out to be dead on).