Robert John Maudsley was born on June 26, 1953, in Speke, Liverpool, England. He was the fourth of twelve children in his family. During his early years, he lived in a Catholic orphanage in Crosby along with his three older siblings. When he was eight years old, his parents retrieved him and his siblings from the orphanage.

After returning home, Maudsley faced routine physical abuse from his father. This continued until social services intervened and removed him from his family's care. Maudsley later claimed that he was raped by his father during his childhood. This abuse had a lasting impact on him and resulted in deep psychological scars.

As he grew older, Maudsley struggled with various challenges. During his teenage years in the late 1960s, he became a sex worker in London. He used the money he earned to support a drug addiction. Due to his struggles with mental health, he attempted suicide several times and eventually sought psychiatric help. In therapy, he told doctors that he heard voices urging him to kill his parents. He believed that if he had acted on these thoughts, fewer people would have suffered later on.

In 1974, Robert John Maudsley murdered John Farrell in Wood Green, London. Farrell had picked up Maudsley for sex and showed him pictures of children he had sexually abused. After the killing, Maudsley turned himself in to the police, saying he needed psychiatric help. He was found unfit to stand trial and sent to Broadmoor Hospital.

In 1977, while at Broadmoor, Maudsley and another patient named David Cheeseman attacked David Francis, a convicted child molester. They locked themselves in a cell with Francis and tortured him to death over nine hours. Following this incident, Maudsley was convicted of manslaughter and sent to Wakefield Prison.

On July 29, 1978, Maudsley killed two fellow prisoners at Wakefield in one day. His first victim was Salney Darwood, who was in prison for killing his wife. Darwood had been giving Maudsley French lessons. Maudsley invited Darwood to his cell and then garrotted and stabbed him before hiding the body under his bed. He then sought another victim, finding William Roberts in his bed. Maudsley stabbed Roberts multiple times and hit his head against the wall. Afterward, he calmly notified the prison staff that they would be short two prisoners during the next roll call.

Throughout these events, Maudsley claimed his victims were sex offenders, stating he viewed them as threats. In 1983, due to his violent nature, he was placed in solitary confinement in a special setup within Wakefield Prison. His confinement was deemed necessary for safety reasons, and he required escort by multiple prison officers when outside his cell.

In March 2000, Maudsley asked for a relaxation of the strict conditions of his solitary confinement or for permission to end his own life. He also requested a pet budgerigar but was denied.