Jeremy Bamber was born Jeremy Paul Marsham on January 13, 1961, at St Mary Abbots Hospital in Kensington, London. His biological mother, Juliet Dorothy Wheeler, was a vicar's daughter who had an affair with British Army Sergeant Major Leslie Brian Marsham. Juliet gave her baby up for adoption through the Church of England Children's Society. When Jeremy was six months old, he was adopted by Nevill and June Bamber, a wealthy couple who lived in a large Georgian house at White House Farm, near Tolleshunt D'Arcy in Essex. Nevill Bamber was a local magistrate and a former RAF pilot. The couple had previously adopted a baby girl named Sheila four years before adopting Jeremy.

Jeremy attended St Nicholas Primary School and then went to Maldon Court, a private preparatory school. In September 1970, he was sent to Gresham's School, a boarding school in Holt, Norfolk. He left Gresham's with no qualifications, which made his father, Nevill, very angry. Later, he managed to pass seven O-levels at The Sixth Form College in Colchester in 1978. During his time at school, it was noted that Jeremy had relationships with both men and women, and his good looks and charm made him popular with many.

After leaving school, Nevill funded a trip for Jeremy to Australia, where he took a scuba diving course, and then to New Zealand. While in New Zealand, Jeremy faced some trouble, reportedly getting ripped off by a drug dealer. He also allegedly boasted about smuggling drugs and broke into a jewelry shop to steal watches. Jeremy returned to the UK and worked in various restaurants and bars, including a job as a waiter in a Little Chef restaurant. Eventually, he agreed to come home and work on his father's farm. Although he disliked the low wages, he lived rent-free in a cottage owned by his father and had some ownership in the family's caravan site business.

A few weeks before significant events in his life, Jeremy admitted to a burglary at the caravan park where he had financial interests. This information came to light after his girlfriend testified against him.

On the morning of August 7, 1985, Jeremy Bamber claimed he called the police to report a shooting at his family’s farmhouse, White House Farm, in Tolleshunt D'Arcy, Essex. He stated that his father, Nevill, had called him to say that Bamber's sister, Sheila Caffell, was acting violently with a rifle. When police arrived, they found Sheila and her mother, June, dead in the parents’ bedroom. Sheila had a rifle against her throat.

Sheila’s six-year-old twin sons, Nicholas and Daniel, were found in their beds upstairs, while Nevill's body was discovered in the kitchen. The investigation revealed that the family had been shot a total of twenty-five times, mostly at close range. Initially, police thought Sheila, who had a history of psychiatric treatment for schizophrenia, was responsible for the murders.

However, during the investigation, a witness named Julie Mugford came forward. She claimed Jeremy had implicated himself in the murders. The prosecution argued that the evidence suggested Bamber was the murderer. They noted discrepancies, such as the lack of a phone call from Nevill, who was severely injured. The prosecutors also pointed out the impossibility for Sheila to have been in control of the rifle during the shootings.

Bamber's defense argued against the evidence presented in court. They claimed there was evidence showing Nevill had called the police that night and suggested the silencer found with the rifle may not have been present during the attacks.

In October 1986, Bamber was convicted of the murders and received a whole life sentence, meaning he would not be eligible for parole. He has since remained in HM Prison Wakefield and has made multiple unsuccessful attempts to have his conviction overturned. Over the years, he has also launched legal actions regarding a share of his family's estate, but those claims were rejected due to his conviction.

In recent developments, Bamber has pursued new legal avenues, claiming he has new evidence that could impact his case. As of March 2021, an application was submitted to the Criminal Cases Review Commission for a referral to the Court of Appeal, based on thousands of documents released in 2011. In 2022, Bamber's legal team submitted additional evidence that could challenge the claims about the use of the silencer during the murders. His case continues to be one of interest in the UK legal system.