Ronald Boyd/Manuel Pardo - Both are serial killers and killer cops, targeted high-risk victims of both genders (Boyd targeted refugees, Pardo targeted drug dealers), and were motivated by a belief they don't deserve to live. Both also were stationed in smaller towns where they committed their killings and were native to the states where they killed people, and both were killed in justifiable killings (Boyd in self-defense, Pardo in an execution).
John Nichols and Sam Russell/Hubert Geralds and Andre Crawford - Both are serial killers of prostitutes with an M.O. of one fiction killer matching the M.O. of a real life killer to some extent (strangulation and stabbing), and because of this, police opened investigations to overlapping murders that left doubt about one killer's guilt because the other's was exposed. In spite of this, the first identified was still reconvicted, and the second one was convicted and incarcerated.
Pablo Vargas/Akku Yadav - Both are serial rapists-turned-serial killers primarily targeting women and girls in their local communities, committed home invasions, were never stopped by the police when reports were disregarded, and were lynched by women who included the living women Yadav attacked. Bladed weapons and castration were partly using to kill both criminals, and the women were released on their own recognizance (a portion of them with Yadav).
Pablo Vargas/Eddie Mosley - Both are serial rapists-turned-serial killers starting with an M.O. of kidnapping and raping women and girls in isolated areas, which resulted in the women communicating with each other, framed innocent men when progressing to serial murder, had insecurities or deficits (Vargas was antisocial and scrutinizing his work performance, Mosley had a low IQ and birth defects), and were tied to numerous violent offenses ranging from rapes to murders after the police's inability to track their crimes for years.
Larry Feretich and Douglas Knight/Gilbert Paul Jordan - All three are serial killers of women (and men in the cases of the fiction killers) by poisoning disguised as fatal substance overdoses. Jordan and Knight manipulated their victims with trust and killed them while they were inebriated. Feretich and Jordan preferred people at bars, and the police disregarded the deaths as serial murders and reported had victim bias in certain cases. The police saved victims from both Jordan and Knight, and Feretich personally stopped the killings, but by targeting the main intended victim, Jim Peters.
Lindsey Vaughn/Freddie Scappaticci a.k.a. "Stakeknife" - Both are serial killers and freelance hitpeople with relations to witness protection (Vaughn's father Jack had her put in protection with him), were leased for contracted killings in other countries besides where mobs they were tied to were stationed (indirectly in Vaughn's case), had codenames to hide their names while they were resourceful (Scappaticci had "Stakeknife"), and surrendered to police in exchange for providing testimony against their affiliates (Scappaticci and the IRA, Vaughn and Cat Adams)
J.B. Allen and Gary Michaels/George Franklin - All three are killers of children, two with children of their own who remembered crimes of them kidnapping and murdering a child when they grew older, which was crucial to arrest and convict their fathers from the repressed memories. In the case of Michaels, Spencer Reid falsely remembered his father having committed the murder, which ended up revealing the real killer.
Trey Gordon/Paul Cox - Both were killers who had a hatred of their parents, took substances prior to their killings that led to periods of unconsciousness in which they killed (most of in Gordon's case) their victims (anti-psychotic medications in Gordon's case, alcohol in Cox's), both stabbed a couple to death with a knife while in an impaired state due to their substance use (Gordon sleepwalked, while Cox was intoxicated), killed their victims in places from their childhoods (Gordon killed his victims in former drug dens and brothels his father took him to as a child, while Cox killed his victims in his former childhood home), believed their victims were their parents, had flashbacks of their unconscious murders, and were remorseful and took measures to ensure they wouldn't kill again afterwards.
Ryan's Gang/Murder of Mary-Ann Leneghan - Both are gangs of kidnappers and murderers responsible for abducting two girls, raping, and torturing at least one of them, then killing one girl and leaving her dead in the woods while the other girl survived an attempt on her life. Also similar to the movie Taken.
Lyov Lysowsky and The Tuareg Brothers/Jurijus Kadamovas and Iouri Mikhel - All three are gangs of serial kidnappers and of murderers for ransom, two groups of Slavic descent, two groups also favoring families in their 30s or middle-aged years, often couples, to kidnap for ransom from their families, before murdering them with two groups. All three groups were violent with their hostages when they were kidnapped regardless of the ransom (Kadamovas and Mikhel and the brothers killed all their hostages, Lysowsky mutilated all his hostages). Lysowsky, Kadamovas, and Mikhel all immigrated into the United States from their home countries and resided in a coastal state.
Brian Matloff/Todd Alan Reed and Gary Hilton - All four are serial killers of women who were murdered in national parks (though Hilton also targeted men), Matloff and Reed left their victims in shallow graves near hiking trails after strangling them, Hilton and Matloff both killed in the Appalachian Mountains.
Kevin Rose and Justin Berry - Both are teenage child pornographers who advertised themselves online in self-made pornography and attracted the attention of child sexual predators.
Steven Fitzgerald/The Doodler - Both are serial killers of gay men who found then at bars and seduced them when getting them alone, bringing props with them as part of their ruse (The Doodler brought a sketch pad, Fitzgerald brought items he stole from the other men he killed), both got the men alone, often in alleyways, and turned aggressive when attacking them. Both also left the men they killed in public areas to eventually be found.
Patrick Jon Murphy/Hiroshi Maeue - Both were serial killers with a fetish for asphyxia that led to strangulation murders of women (though Maeue also killed male victims), had long standing histories of asphyxiation murders before their major sprees were noticed by the police, arranged consensual meetings with victims online under false pretenses, and were found out to have committed their first crimes separate from their website murders after their more recent crimes were discovered.
Eddie Mays/Herbert Mullin - Both are schizophrenic devolving killers whose lives were derailed after reckless psychotropic drug use, which degraded their capacities in the directions they took in their murder sprees under the pretense of grandiose delusions, their murders varying between numerous people, using several different weapons, and often involved extensive evisceration. Both also stalked and attacked an object of fixation of theirs at the ends of their sprees (Eddie kidnapped his neighbor, Mullen killed his former drug dealer).
Charles Johnson/Emmett Till - Both are victims of hate crime violence by racist white mobs resulting from their alleged sexual offenses against white women from decades ago when they were just teenagers.
Gina King/John Hinckley, Jr. - Both are schizophrenic stalkers and violent criminals obsessively following notorious entertainment celebrities and harassing them before their violent crimes with numerous psychotic messages to get their attention. Both then escalated to murder attempts (which only Gina succeeded in) to impress their stalking victims, emulating their notorious performances in the staging of the scenes where the victims were found after being attacked.
John Vincent Bell, Jimmy Hall, Ronald James Underwood, John Myers, and Dustin Eisworth/Charles Bronson - Bronson, Bell, Myres, and Einsworth are all criminals incarcerated for aggravated offenses, only to increase their time in prison and be difficult prisoners with as difficult responses to their pugnacious fights against other prisoners and guards.
The Corrupt Corrections Officers/The Corcoran State Prison "Gladiator Fighting" Conspiracy - Both are violent rings of corrupt prison guards in high-ranking prisons responsible for pitting inmates against each other in fights to the death, and otherwise personally killing them when they disobey or lose.
Robert Reimann/Daniel Camargo and Marc Dutroux - All three are serial killers and rapists with female partners as accomplices, Reimann and Camargo unable to have sex with their partners, and Reimann and Dutroux holding two female victims captive at the same time.
Colin Bramwell/Peter Sylvester - Both are murderers and serial snipers contracted by friends to kill someone familiar with the friends, shooting at innocent bystanders in the process as intentional collateral to divert suspicion away from their motives.
Animal/Herman Bell - Both are murderers and cop killers with an M.O. of calling 911 to lure dispatch officers into an ambush, only to shoot them when they're in a vantage point to kill them from.
Luke Dolan/Scott Panetti - Both are psychotic killers responsible for killing their parents (in-law in Panetti's case) before getting into standoffs involving their wives and children, both motivated by paranoid possession delusions that their families were in danger ironically provoking them to kill and take hostage their families.
Bruce Morrison/Joshua Powell - Both are fathers and presumed murderers of both their wives, who disappeared, and then later their children, who were later found dead, the murders happening years apart and garnering much attention with the fathers as the prime suspects in the case.
Jason Clark Battle/John Leonard Orr - Both are killers with malignant Hero syndrome with numerous decorations in their service as enforcement and rescue officials, each killed four people precisely of different victimologies, were active in the jurisdictions they were stationed in, and were even present at the scenes of their own crimes.
Jason Clark Battle/Richard Angelo - Both are narcissistic serial killers and assailants with licensed positions in the settings they work in, consistently endangering civilians with the intention of taking the glory of allegedly trying to save them, feeling a sense of power from the murders and assaults, and specifically waiting until their victims were on the brink of death, not caring either way whether they actually saved their victims or not.
Dinah Troy/Rose Kennedy - Both are matriarchs of highly influential political families alleged to have been affiliated with mobsters and arranged kidnappings of women in the lives of their sons in politics with the interest in benefiting their family's legacy.
J.B. Allen/Edward Edwards - Both are serial killers with their victims including children over the span of years, had daughters in their lives who grew into adults, and were turned in by their mature daughters who dug into their families' pasts and found out their fathers' crimes by matching the details of their family history and lives' timelines.
Bea Adams/Natasha Cornett - Both are leaders of gangs responsible for turning at least one of the men in the gang into family annihilator killers, traveling on the road with the group in a shared car and having a resentment of people they saw were living more elite or proper lives than the group.
Everett Lynch/Terry Peder Rasmussen - Both are cross-country serial killers, mostly of women and girls, responsible for killing their daughters, took on numerous aliases, killed in multiple states, entered into fraudulent marriages, killed their romantic partners, and had more murders the police hadn't tracked until the killers were even discovered.
Johnny Ray Covey/Juan Arreola-Murrilla - Both are multiple killers and rapists of Latina women on the same day of each year one of their victims were killed, gagged them before killing them with asphyxiation (Covey killed by drowning, Arreola-Murrilla killed by strangulation), used ruses to gain their victims' trust, were tracked by task forces unsuccessful in apprehending the killers until years after the case went cold, had descriptions of the killers from witnesses, and also attacked children (Covey kidnapped children to watch their nannies be tortured to death, Arreola-Murrilla killed an unborn child of one woman he murdered)
Marc Clifford/George Geschwendt - Both are family annihilators of families they were jealous of and f families responsible for always insulting them and making them feel less important, killed all their murder victims by shooting, and targeted all members of the family (only Geschwendt succeeded in killing all the family).
Marc Clifford/Keddie cabin murders - Both cases are family annihilations involving different M.O.s in the murders (bludgeoning and stabbing in Keddie, shooting and strangling with Clifford), with one family member going missing and later also being found murdered, and leaving behind one multiple witnesses at the scene of the massacre, one each who was running out of the house. In both cases, the murder weapons weren't found until later, and unhappy homes and marriages were presumed motives. The affair resembles the admitted one by Arnold Schwarzenegger.
Arthur Malcolm/George Reardon, Eugênio Chipkevitch and Earl Bradley - All four are pedophilic serial rapists of children who were patients of each, Malcolm and Bradley setup play areas with toys as ruses for the children, all four worked in medical fields, and Malcolm, Reardon, and Chipkevitch took trophies from the kids who were sexually abused, which would be undoings of the pedophilic rapists.
Mike Hicks/Dorothy Jane Scott - Both are stalker cases beginning with harassing messages to targeted women with families, including messages with flowers, before abducting them when they're not far from people they're close to and meaning threats to their life.
William Meeks/Andrew Kehoe - Both are serial bombers, school bombers, and mass murderers responsible for school bombings that massacred over one hundred people, killed family members, and attempted suicide with a final bombing (only Kehoe succeeded).
Kyle Zorgen and Donna Mangold/Alicia Kozakiewicz and Kacie Moody - All three cases are cases of kidnappings of girls who were lured by fake online messaging profiles. With Meg Callahan and Kacie, the fake profile involved a friend knowing about the profile shortly before at least one of the girls were kidnapped, ending with a murder where the victim was found dead in isolation (though where Kacie was murdered, kidnapper Kyle was instead). For Meg and Alicia, the same ruse and kidnapping was used, but their guardians were trusting and proud of their responsibility, and it led to images of the girls in captivity being sold online shortly before their rescue.
Benjamin David Merva and Dionathan Celestrino - Both are cult leaders, serial kidnappers, and serial kidnappers with the same rituals for murdering victims of various victimologies, were arrested along with portions of their cults for the crimes and willing participation, had signatures with the victims' bodies (Celestrino posed them in cross positions postmorten, Merva cut their hyoid bones out while they were still alive), had survivors (Owen Quinn and "Carla", accordingly) and were inspired by criminals before them (Benjamin Cyrus and Francisco de Assis Pereira, accordingly).
Jeffrey Charles/Eric Smith - Both are child killers of children with aggression and sociopathy, killed their victims by bludgeoning, murdered and left their victims in forests, and even uncannily resemble each other.
Cat Adams and Joanna Dennehy - Both are misogynistic, psychopathic serial killers with a preference for targeting men, have had bisexual relationships, particularly with male partners in the public world, including victims she lured through seduction, and female inmates in prison, alleged to have reservations of which people they did and didn't prefer as victims, and always worked with accomplices no matter the crimes they tried to commit.
Jeffrey Whitfield and William Pratt/Alfredo Galán - All three are serial killers with an M.O. of shooting victims, an obsession with fame, started leaving calling cards when they started getting media attention from an item at the scene that led to their nicknames, and had mental illnesses that included social problems.
Michael Huang/wikipedia:New Bedford Highway Killer and wikipedia:Lisbon Ripper - All three are serial killers of women in favored local hunting grounds, alleged to be connected when investigations spread overseas, and resulted in consultation of the FBI to see if the cases were connected, finding additional murders in numerous other countries besides the two were the primary serial killer cases were centered.
Earl Bulford/David Berkowitz - Both are serial killers with early petty criminal records in their youth, targeted victims out in public areas, including couples, had absent birth mothers in their childhoods, killed the majority of their victims at the scenes of the crimes, always used the same murder weapons, worked in blue-collar jobs, had exposure to animals that fit into their pathologies (Berkowitz was bitten by a dog and would hallucinate barking, Bulford worked in taxidermy), and committed more inexperienced attacks before more prepared, ritualistic serial killings.
James Thomas/The Phantom Killer - Both are serial killers of couples targeting them in home invasions and in their cars, profiled as impotent sadists, killed their victims by shooting while they made love, stalked their victims beforehand, and left the couples they murdered at the scenes where they were killed.
The Rogue Deputies/Jeff Davis 8 - Both are cases of serial murders of prostitutes in small towns scattering the places where the murdered prostitutes were found, revealing police corruption, and leading to more murders between various parties in the town.
Aaliyah Nadir and Hassan Nadir/Betty Mahmoody and Sayyed Bozorg Mahmoody - Both are Middle Eastern couples with the husband being abusive to the wife and affiliating with terrorists, causing the wife to flee to America with her children and turn on the husband by selling out his associations.
Eric Carcani/Sheila Bellush, Betty Mahmoody, Shiori Ino - All four are cases of battered wives running from abusive marriages to protect themselves, two of them with support from people close to them, two of them still with children. In three cases, the spouse ordered a hitman to track the wife down and shoot her out of revenge and to silence her testimony.
Tess Mynock/Polly Bartlett - Both are female serial killers who run lodges they use to lure guests into for the sake of poisoning them and then burying them in natural lands on their properties.
Cormac Burton/Juan Corona - Both are serial killers of men in rural areas surrounded by natural, use machetes as a signature murder weapon, left all their victims in mass graves in ditches, had parents and siblings, and suffered traumatic events that made them snap and ingrained in their minds before they became serial killers (Burton's beloved dog was released by his father and brother, Corona witnessed a flood of crop fields which scarred him from his fear of water).
Kevon Winters/Harold Shipman - Both are prolific "angel of death"-type serial killers whose mothers were both euthanized, killed their victims with drug overdoses, and attempted to commit suicide (only Shipman succeeded).
Dylan Kohler/Luke Helder and ManMan - Both real life criminals are serial killers with severe psychosis committing crimes on selected properties to trace symbols om maps, were arrested in confrontations with police, had previous idols (Helder had Kurt Cobain, Kohler had Rodney Garrett), and were presumed to have sent grandiose letters the police eventually found (though that was only true with Helder writing a manifesto). Kohler resembles main anti-hero protagonist Frank Zito in the movies, killing blond women just to steal their hair, as far as scalping them, to make blond wigs out of their hairs in honor of their objects of affection.
The Horsemen/Alexandria family hostage crisis - Both groups are hostage-takers with the motives of having family members released from jail, threatening the lives of all present hostages at the scene if demands weren't met. Possibly derives from Dog Day Afternoon as well.
Matt Franks/Arthur Bomar - Both are killers and sadists targeting young women and girls who competed in sports and having escalated in their crimes the more they committed, had a similar M.O. of confronting each victim before murdering them.
Rodney Garrett/Ted Bundy, Gary Ridgway, and Anthony Sowell - All four are serial killers of women responsible for kidnapping, murdering, and burying them undetected for years before police suspected and arrested them, especially when their burial sites were revealed. Garrett and Bundy both had partners they treated with respect before they were ousted as serial killers.
James Stanworth/George Geschwendt - Both are family annihilators motivated by revenge out of inferiority complexes, breaking into the homes before assaulting all family members and trying to kill them all (only Geschwendt succeeded), and prepared with weapons and clothes for forensic countermeasures before the massacres.
Eric Miller/Jeffrey MacDonald - Both are fathers of murdered families convicted of their murders and proclaiming innocence by alleging their families died due to intruders in their homes (which was only true with Miller).
Donald Sanderson/Sam Sheppard - Both are convicted and incarcerated whose convictions were overturned when their innocence was proven by identifying the evidence supporting their claims of the murders of their spouses by home invasions.
Terrance Wakeland/Maury Travis - Both are black-American serial killers of black-American women and girls motivated by sexual sadism, brutalizing their victims to death, leaving them to be found in open areas, sending messages to be publicly found, and ending up being found out by their own M.O.s of their crimes.
William Lee/Peter Samuel Cook - Both are serial burglars and rapists responsible for stalking women, leaving harassing messages for them to find when they're not raped, wearing a mask, and being caught at the scene of a crime.