Shani Warren: Man guilty of murdering woman found bound and gagged in lake 35 years ago

A man has been found guilty of murdering Shani Warren, who was found bound and gagged in a lake in 1987, and of kidnapping and raping a teenager six years earlier.

Donald Robertson, who did not attend his trial, was described by a senior crown prosecutor as a “dangerous and deadly predatory sex offender who attacked women over almost three decades, using violent threats to get what he wanted”.

The 66-year-old had a “long and horrific list of previous convictions”, police said, and he was found guilty of the crimes against both women by unanimous verdict at Reading Crown Court on Tuesday, following the discovery of new DNA evidence.

He was convicted of the false imprisonment, indecent assault and murder of Ms Warren over a period of three days in April 1987. The 26-year-old, who lived in Stoke Poges in Buckinghamshire, was found in Taplow Lake, her wrists having been tied with a car jump lead and her ankles bound by a tow rope.

Her brother, Stephen Warren paid tribute to his sister – who he called a “force of energy, hope and positivity” – and said her loss had left a “gaping hole” in their family, with her parents having died last year with her murder “never resolved in their minds”.

“On Good Friday, 1987, after mowing the lawn, another duty she resolutely took on, she ‘popped out’ to dispose of the grass cuttings, get some food, and buy a card and Easter egg for an ex-boyfriend. She was due back, likely in an hour or so,” Mr Warren said in a statement.

“But it is one of life's tragedies that everything can be destroyed in an instant. Somehow or other, Shani encountered the serial rapist Donald Robertson, whose practice was to attack unaccompanied young girls and women, terrifying them into submission with vicious threats and abuse.

“We cannot imagine what the last moments of Shani’s life must have been like, but you may agree that no punishment is enough for her attacker; a psychopath and a coward who lacked the courage to attend court, or even to give evidence via a live link.”

Robertson was also found guilty of the kidnap and rape of a 16-year-old girl, who cannot be identified, on 16 July 1981, in Farnham Lane, Slough, which took place just three months after he was released from prison for burglary and the attempted rape of a 15-year-old girl who was home alone in Slough.

Following Tuesday’s verdict, the woman raped by Donaldson aged 16 – who gave evidence at the trial – branded him “the monster that put my life in turmoil”, adding: “Justice has been done and I can finally get some closure.”

Police hailed her “bravery and courage” in coming forward and said it is “a regret” there had not been enough evidence to charge Donaldson at the time.

The trial heard that she had been asked to pick out her attacker – who pounced on her as she walked home – from a line-up at a police station just a few weeks after the incident, and to “touch or otherwise clearly indicate” which one he was.

She did not identify anyone while in the room but shortly afterwards she tearfully told police she believed it was the man standing in Robertson’s position. Officers decided there was not enough evidence to justify charging him and he was released.

Four days later, Robertson raped a 14-year-old girl who had been riding her bicycle in Farnham Royal, a crime for which he pleaded guilty in October 1981 and spent a little over five years in jail.

It was just four months after his release from prison in December 1986 that he attacked and murdered Ms Warren.

While he had evaded justice for Ms Warren’s murder for decades, he is already behind bars as a result of a separate effort by the police’s cold case team, which saw him convicted in 2010 for the rape of a 17-year-old girl who was walking home after missing her last train.

That crime took place less than two months after he murdered Ms Warren and only a few miles from Taplow Lake, where her body was found.

As his latest trial drew to a close this week, jurors took just seven hours and 18 minutes to reach their verdicts.

UK news in pictures

The serial attacker was charged last year after police found new DNA evidence – described by prosecutors as the “cornerstone” of the latest case – with traces matching Robertson’s discovered on the underwear of both victims, and on a mouth gag used on Ms Warren.

Thanking Ms Warren’s family for their support and patience, Thames Valley Police’s major crime review team’s principal investigator, Peter Beirne, said: “I’m sorry that it took so long to bring Robertson before the court, but we’ve only been able to do that as a result of advancements in forensic science. It was not as a result of any lack of effort on behalf of the police.

“It was just that unfortunately, at that time, there was not the evidence to enable us to charge Robertson.”

Mr Beirne also praised woman raped by Donaldson in July 1981 for her “bravery and courage in coming forward when we spoke to her” and hailed her “strength of character” in going to court to give evidence during the trial.

Robertson’s failure to attend his trial “speaks volumes” to his character, Mr Beirne said, labelling him “a coward, [who] wasn’t prepared to stand up and answer to the charges which were put before him”.

“Most victims have said he's either had a weapon or has told them he's had a weapon and they've been subjected to the most horrendous acts upon their life,” Mr Beirne added.

“In regard to Shani, obviously unfortunately it cost her her life. It is difficult to put into context what these young girls and women went through, but without doubt, Robertson is an evil and dangerous man.”

Robertson did not give evidence in his defence, and his lawyer called no witnesses but claimed another convicted rapist guilty of crimes around that time involving tying women up and attacking them could have been the culprit.

He also referred to evidence from a pathologist at the time of Ms Warren’s death stating she could have tied her own wrists and ankles, making it a suicide, and argued that even if a third party was involved, the possibility of someone falling into the water after having been tied up and assaulted, could not be ruled out.

Robertson will be sentenced at the same court on Thursday afternoon, and Mr Justice Wall told jurors on Tuesday that he would consider whether to recommend that Robertson “is never released” from prison.

Additional reporting by PA