Season 1

The events that transpired at 25 Cromwell Street in the UK, where a seemingly normal father and mother (Fred and Rose West) tortured, raped and murdered young women, including their own children.

Profile of serial killer Dennis Rader, who preyed on families in Kansas for 30 years, and called himself BTK to draw attention to his preferred murder method - bind, torture and kill. Rader's narcissistic nature proved to be his downfall when, after years of mocking the police officers attempting to find him, a careless mistake exposed his identity

The case of Green River killer Gary Leon Ridgeway who was arrested on 30 November 2001 after 19 years of police searches. The offender is recognised as the most prolific murderer in US history, having slayed at least 48 women. A warrant was granted to search his property in 1987 but no evidence was found at the time, it was only after a breakthrough in DNA technology in 1999 that the case was reopened

The case of Austrian Jack Unterweger who, after serving a 14-year spell in jail for the murder of a girl in 1974, went on to become a celebrated media figure and an example of the reform system's effectiveness. However, since his release, it transpired he had killed up to 11 more people across Europe and America and he hanged himself in his cell after being given a life sentence without parole

The case of Ivan Millat, who killed at least seven backpackers in New South Wales, Australia, during the early 1990s. Police were initially confounded by the marked differences in the murders and it was suggested two offenders could be on the loose. However, evidence eventually began to mount against Millat, who had been charged with the rape of two women in 1971, and it was ascertained he was the only culprit

The case of Phoenix Strangler Sipho Thwala, who was sentenced to 506 years in jail in March 1999 when he was convicted of the murder of 16 women in Durban, South Africa. The police search was initially hampered as the bodies had been burned, but with the help of psychological profiler Micki Pistorius and DNA samples which matched those from a past attempted rape, Twala was eventually brought to justice.