Male Killers

Aaron Campbell became one of Scotland's most infamous child killers after abducting and murdering seven-year-old Megan Montgomery in Airdrie, North Lanarkshire, in 2020. Campbell lured the child from outside her home before killing her and concealing her body in nearby woodland. Following an extensive police investigation, he was convicted of murder and sentenced to life imprisonment with one of the longest minimum terms imposed in Scotland for the murder of a child.

Aaron James McKinney is an American convicted murderer responsible for the fatal beating of 21-year-old University of Wyoming student Matthew Shepard near Laramie, Wyoming, in October 1998. McKinney and accomplice Russell Henderson kidnapped and robbed Shepard before taking him to a remote location, where McKinney repeatedly struck him with a handgun and left him tied to a fence. Shepard died six days later. McKinney was convicted of felony murder, kidnapping and aggravated robbery and received two consecutive life sentences without the possibility of parole.

Adam Matos murdered his former girlfriend Megan Brown, her parents, and her new boyfriend in a brutal quadruple homicide in Hudson, Florida, in 2014. Matos killed Megan, 27, her parents Gregory and Margaret Brown, both 52, and Megan's new boyfriend, Nicholas Leonard, 37, at the waterfront home where Matos had been living with members of the Brown family. Megan and Gregory were shot, while Margaret and Leonard were killed by blunt-force trauma. Matos subsequently moved the bodies from the property and left them stacked in a nearby field, where they were discovered during the investigation.

Adam Montgomery is an American father who was convicted in 2024 of the second-degree murder of his five-year-old daughter, Harmony Montgomery. Prosecutors alleged that he fatally assaulted Harmony in December 2019 before concealing her death, transporting her body and later disposing of her remains. Harmony was reported missing nearly two years later, prompting a nationwide investigation. Montgomery was also convicted of second-degree assault, abuse of a corpse, falsifying physical evidence and witness tampering. He was sentenced to a minimum of 56 years' imprisonment, with the murder sentence to be served consecutively to his other sentences.

Adolf Eichmann became one of the most infamous figures of the Holocaust as a senior SS officer responsible for coordinating the deportation of millions of Jews and other persecuted groups to Nazi ghettos and extermination camps during the Second World War. Following Germany's defeat, Eichmann fled Europe and lived under a false identity in Argentina before being captured by Israeli intelligence in 1960. He was convicted of crimes against humanity, war crimes, and crimes against the Jewish people before being executed in 1962.

Adolfo de Jesús Constanzo became one of Mexico's most notorious serial killers after leading a violent criminal cult that combined ritualistic beliefs with narcotics trafficking during the 1980s. Operating primarily in Mexico City and Matamoros, Constanzo and his followers carried out numerous murders as part of ceremonies they believed would provide supernatural protection and success. The discovery of multiple victims at his ranch in 1989 exposed one of the most disturbing criminal conspiracies in Mexican history.

Adrian Ernest Bayley became one of Australia’s most notorious violent offenders after abducting, raping and murdering Jill Meagher in Melbourne in 2012. The murder shocked Australia because Meagher disappeared while walking home through Brunswick after a night out with friends, sparking enormous public fear and grief across Victoria. Bayley’s extensive violent criminal history later generated intense outrage after it emerged he had previously committed multiple sexual and violent offenses before being released on parole. The case became a defining moment in Australian discussions surrounding parole laws, repeat sex offenders and women’s safety, while Jill Meagher’s death triggered massive public vigils and nationwide mourning.

Alphonse Gabriel "Al" Capone became one of the most notorious organized crime figures in American history after dominating Chicago's underworld during the Prohibition era. As the leader of the Chicago Outfit, Capone oversaw bootlegging, gambling, prostitution, extortion, and numerous violent crimes throughout the 1920s. Although strongly linked to many murders, including the infamous Saint Valentine's Day Massacre, Capone was ultimately convicted of tax evasion rather than homicide. His criminal empire and public notoriety made him one of the most recognizable gangsters of the twentieth century.