The “babes in the wood” killer, Russell Bishop, has been jailed for life and ordered to serve a minimum of 36 years for the murder or two schoolgirls more than three decades ago.

Bishop, now 52, sexually assaulted and strangled Karen Hadaway and Nicola Fellows in October 1986, when they were nine, in woods about half a mile from Moulsecoomb, the area of Brighton where the girls lived.

Sentencing him at the Old Bailey, in London, on Tuesday, Mr Justice Sweeney said: “I have no doubt that you were a predatory paedophile. The terror that each girl must have suffered in their final moments is unimaginable.”

The breakthrough in the longest running case in the history of Sussex police came when scientific advances led to DNA evidence providing what the Crown Prosecution Service described as a “one-in-a-billion” match linking Bishop, a convicted paedophile, to a sweatshirt found at the scene of the murders.

Bishop had been found not guilty in 1987 but after the new evidence emerged the acquittal was quashed, paving the way for a retrial. On Monday, after an eight-week trial, Bishop was convicted, ending the families’ 32-year fight for justice.

Facebook Twitter Pinterest Karen Hadaway (left) and Nicola Fellows. Photograph: Sussex police/EPA

Bishop returned to live in the Brighton area after his acquittal, but less than three years later, in February 1990, he committed offences involving the attempted murder, kidnapping and indecent assault of a seven-year-old girl in the Whitehawk area of the city. After she identified Bishop as her attacker, he was convicted in December 1990.

The court heard that fibre transfers linked Bishop’s sweatshirt to Karen and Nicola, the murder scene and his home. The court heard that he punched Nicola in the face to “subdue” or “punish” her for being disrespectful to his teenage girlfriend earlier that day.

Bishop tried to explain the forensic evidence by claiming he had touched the girls to feel for a pulse on the day after the killings, when he had joined the search for them and was nearby when they were found. However, two teenagers who had spotted the bodies insisted he could not have been that close to them.

Bishop’s defence team, under his instructions, also cast suspicion on Nicola’s father, Barrie, reducing the 69-year-old to tears.

In a victim impact statement, Karen’s mother, Michelle, described Bishop as an “evil monster” and said having to go through a second trial was “traumatic and heartbreaking”.

Sue Eismann, Nicola’s mother, said the death of her daughter had turned her world upside down and spoke of her “sheer hate” for Bishop.