Male Killers

John Duffy was a British serial killer and rapist known as one of the "Railway Killers," responsible for a series of attacks on women near railway stations in London during the 1980s. He committed his crimes alongside accomplice David Mulcahy. Duffy was eventually arrested and convicted, receiving a life sentence. His case was significant in the development of offender profiling techniques in the United Kingdom and remains one of the most notorious series of crimes in London’s history.

John Franklin Howard is an American man convicted in connection with an attempted murder-for-hire plot against his wife in Texas. The case gained attention due to the level of planning and the use of a hired attacker. He was later convicted and sentenced to life imprisonment.

John Haigh, known as the "Acid Bath Murderer," was a British serial killer who murdered victims and disposed of their bodies using sulfuric acid in the 1940s. He targeted wealthy individuals and used fraud to gain access to their assets. Haigh was eventually arrested and convicted after investigators uncovered evidence of his crimes. He was executed in 1949, and his case remains one of the most infamous murder cases in British history.

John Asher Farrell Villarreal became known in American criminal history after the murders of a Texas couple who stopped to help him while he was hitchhiking on Christmas Eve in 2014. Prosecutors alleged Villarreal repaid the victims' kindness with extreme violence, killing both occupants before stealing their vehicle and attempting to evade capture. The case attracted significant attention because of the apparent randomness of the attack and the betrayal involved. Investigators argued the victims had no prior connection to Villarreal and had simply offered assistance to a stranger. The murders shocked the local community and became a tragic example of a good Samaritan encounter ending in deadly violence.

John Wayne Gacy was an American serial killer and sex offender who murdered multiple victims in Illinois during the 1970s. He became widely known for maintaining a public image as a community figure while committing crimes in secret. Gacy’s case gained notoriety due to the scale of his offences and the contrast between his outward persona and his actions. He was later convicted and sentenced to death, becoming one of the most infamous serial killers in U.S. history.

Joji Obara is a Japanese serial offender responsible for numerous sexual assaults and murders, including the high-profile deaths of Lucie Blackman and Carita Ridgway in the early 2000s. His crimes shocked Japan and the international community due to their scale and brutality. Obara targeted women, often drugging them before carrying out prolonged assaults. His eventual arrest led to a lengthy trial, resulting in a life sentence. The case exposed gaps in law enforcement responses and highlighted the dangers faced by women working in nightlife industries.

Henry Jonathan Valencia, often referred to as Jonathan Valencia, became known in true crime coverage after the murder of teenager Nosiah Santos during a public confrontation that prosecutors described as emotionally charged and deeply personal. Investigators alleged the killing stemmed from a secret relationship, escalating jealousy, and mounting tension between the two young men before the fatal shooting occurred. The case generated major online attention because portions of the confrontation and aftermath were captured on surveillance footage and witness recordings. Prosecutors argued Valencia intentionally targeted Nosiah Santos during the encounter before opening fire in front of witnesses. The combination of hidden relationship allegations, emotional conflict, and public violence turned the case into a heavily discussed modern youth homicide prosecution.

Joran van der Sloot became internationally infamous after years of deception, manipulation and violent criminal behavior connected to multiple international investigations. Long before receiving a murder conviction in Peru, van der Sloot had already become one of the most recognizable criminal suspects in the world due to his constant media appearances, contradictory statements and apparent obsession with controlling public narratives surrounding himself. Van der Sloot developed a reputation as a pathological liar who repeatedly exploited media attention, manipulated investigators and inserted himself into global headlines for nearly two decades. His later murder conviction and extortion schemes cemented his image as a narcissistic and dangerous offender whose crimes extended far beyond a single homicide investigation.