John David Guise Cannan was born on February 20, 1954, in Sutton Coldfield, Warwickshire, England. His father, Cyril Cannan, served as a flight lieutenant in the Royal Air Force during World War II and later worked as an engineer. His mother, Sheila Cannan, was a housewife. John grew up in a middle-class family and was sent to Keyse private school for boys at the young age of four. He continued his education in public school until he turned 15.

During his childhood, Cannan claimed he experienced severe trauma when he was sexually abused by a teacher between the ages of seven and eight. This abuse lasted for several months, leaving him feeling ashamed and anxious. As a result of the trauma, he developed a stammer and became increasingly afraid of school. At nine years old, he was removed from the school and began to seek medical help for his anxiety.

Cannan's relationship with his father was marked by conflict. His father was known to be critical and had a temper that could change unexpectedly. By the time he was 17, Cannan spent three months in the merchant navy before starting work as a car salesman in his father's company.

In May 1978, Cannan got married to June Vale, and together they had a daughter. However, by 1980, he left his family. Around this time, he began to struggle with alcoholism, often avoiding going home by spending time in bars and nightclubs.

John Cannan's criminal activities escalated significantly over the years. Starting from the late 1970s until 1980, he was associated with a series of rapes known as the "House for Sale Rapist" incidents. During this time, twenty women were assaulted in homes that were on the market in the West Midlands. The rapes ceased when Cannan began a relationship with Sharon Major.

In 1980, after leaving his wife, Cannan attacked Major when she attempted to leave him. He strangled her during an assault, threatening to kill her, but she managed to escape. Later that year, he robbed a petrol station while threatening staff with a knife, and in March 1981, he raped a shop assistant in Birmingham at knifepoint.

In June 1981, Cannan was sentenced to eight years in prison for his crimes, but he served only five years. Upon his release, he continued to engage in violent behavior. In October 1986, he raped a woman in Reading, using a knife to threaten her. Although he was arrested, the evidence was not strong enough to charge him until 1988 when improved DNA testing linked him to the crime.

Cannan's most notable crime was the murder of Shirley Banks in October 1987. She was last seen after going shopping. Her husband reported her missing when she did not return home. Police suspect Cannan held her overnight in his flat and forced her to call into work to claim she was sick.

Cannan was arrested on 29 October 1987 for a separate assault but was quickly linked to Banks' disappearance when her car was found in his garage, painted over. While investigating this case, police received multiple tips about unusual activity near his flat and discovered incriminating evidence, including a raincoat with bloodstains.

On 3 April 1988, six months after Banks vanished, her decomposed body was found in the Quantock Hills. The autopsy revealed that she had been killed by blunt force trauma to the head.

Cannan faced trial and was found guilty of her murder in 1989, along with other charges such as rape and attempted abduction. He received a life sentence.

Cannan was also linked to the murder of Sandra Court in May 1986. Her body was discovered in a water-filled ditch near the River Avon. Cannan had been in Bournemouth on the day of her murder, supported by a parking ticket. Two hairs matching Court's DNA were found in a car associated with Cannan, but this evidence did not lead to a prosecution.

Cannan became a prime suspect in the 1986 disappearance of Suzy Lamplugh. The police believed he had killed her, but there was not enough evidence for charges. Throughout the years, there were multiple investigations and searches for both Lamplugh's and Court's bodies, but neither was recovered from the suggested sites.

Cannan continued to deny his involvement in these crimes while serving his life sentence. He was reported to be receiving palliative care in prison at the end of his life. Ultimately, he died in November 2024 from natural causes while still imprisoned for his earlier crimes.