A "dangerous predator, fantasist and manipulator" has been found guilty of murdering six-year-old Rikki Neave for his own sick sexual gratification.
James Watson, 41, was convicted by majority verdict at the Old Bailey of murdering little Rikki in 1994.
A string of blunders by blinkered detectives originally led to Rikki’s mother being charged with his murder while the real killer escaped justice for 28 years, it can now be revealed.
Forty-five key exhibits were lost or discarded by Cambridgeshire Police, including the coat used to strangle Rikki and the rest of the clothing he was wearing at the time of his death.
The "catalogue of failures" can be revealed after Watson was today convicted of murdering the six-year-old in woodland near his home.
Watson, then 13, thought he had got away with murder after detectives became convinced that Rikki's mother was the killer despite a wealth of evidence to the contrary.
Ruth Neave, 53, was acquitted of the killing in 1996 but was jailed for seven years after admitting child cruelty in relation to Rikki and two of his sisters.
Watson's barrister Jenni Dempster, QC, told the Old Bailey that some senior officers remained convinced that Ms Neave had killed her son after her trial.
Ms Dempster said this meant that no "proper investigation was made at any stage before 2015."
She told a pre-trial hearing, which can now be reported: "One example of the catalogue of failures and mistakes was the destruction, and sometimes loss without trace, of key exhibits."
Rikki's coat was returned to Ms Neave by police in 2002 along with his white shirt, underpants and shoes. She later disposed of them in a wheelie bin.
Ms Dempster said no cold case reviews were done by Cambridgeshire police for 20 years after Ms Neave was cleared.
Reading a note written by one detective after her trial, Ms Dempster said: "Despite there being no eyewitnesses, the evidence against Ruth Neave is very strong. It appears to be a perverse decision by the jury to find her not guilty."
A total of 18 body tapings taken during the post mortem have vanished along with urine, stomach contents, nail clippings and a nasal swab.
Ms Dempster said: "Forty-five key exhibits have been returned, destroyed or lost following Ruth Neave's acquittal."
At her trial, Ms Neave was accused of murdering her son at home and later transporting his body to the nearby woodland where he was found.
But an expert who examined Rikki's Clarks shoes at the time discovered mud on the left sole which indicated that he had walked into the wood where his body was found and never walked out again.
This was not used by the original police investigation or disclosed to Ms Neave's defence team.
Rikki's last meal of Weetabix put his time of death at around midday on November 28, shortly after he was seen with Watson, the trial heard.
Ms Dempster said the original investigation did not treat Watson as a suspect or even significant witness despite him telling police a week after the murder that he had seen Rikki on the day he died.
Former Assistant Chief Constable for Beds, Cambs and Herts Police, Paul Fullwood, who spearheaded the new probe, said he ordered a forensic review of the case in 2015 after realising something was "not quite right".
Mr Fullwood said the original hypothesis of how Ms Neave was supposed to have killed her son was "fanciful".
He said: "Their view was that she strangled him at her home address, she then called the police, the police turned up at her home and searched it. It's alleged that the body was hidden there somewhere.
"The police have then gone searching for Rikki and she is supposed to have put him in a pushchair, pushed him halfway across the estate, dumped him in the wooded area, stripped him naked and then dumped his clothes and then gone home.
"My professional view, having dealt with lots and lots of jobs, child deaths, child murders, was that it was just fanciful. From my perspective I just couldn't understand it."
Mr Fullwood ordered officers with no connection with Cambridgeshire police to investigate because of fears there was an "unconscious bias" in the force.
Mr Fullwood said: "My professional view on this is that I think they became so focused on Ruth Neave being responsible that they didn't keep an open mind.
"They discounted other opportunities where James Watson comes into it."
Watson was charged after his DNA was found on tapings taken from Rikki's clothes that had been retained.
Mr Fullwood said: “This trial happened as a result of our 2014/15 review and 2015 re-investigation. From the outset, we were determined to review all of the evidence available from the original case and understand what it told us about Rikki’s death and the person responsible for his murder.
“Unfortunately, some of the exhibits from the original case were damaged in a flood and others were given back to the family following the original trial and the new team were never able to find them.
"This would no longer happen in an unsolved murder case we now keep all materials until an investigation is solved.
“Thankfully we still had tapings from Rikki’s clothes which proved crucial in providing the team with key forensic evidence for this case.
“As a new team we can’t say why some evidence was not used originally but we know that this would not happen now and our re-investigation has resulted in the person responsible for Rikki’s death finally being found and dealt with.
"Providing Rikki’s family with long awaited justice.”
Ms Neave said: “The last 28 years have been horrible because even though I was cleared of murder there was still the taint of guilt.
"But I'm not interested in clearing my name because in my heart I have always known I didn't kill him."
The heartbroken mother added: "The only thing now is to close this chapter in my life and open a new one. I wonder what Rikki would be like today, married, children? Who knows?
"But this monster has taken that all from me and my daughters."
Rebecca Harvey, Rikki's sister, said in a statement through police that the family was "relieved" that justice had been served but was heartbroken their dad was "no longer with us to see his son's justice".
Rikki's two younger sisters Rochelle and Shelley Neave said in a joint statement that the youngster can now "rest in peace".
They said: "It will never take the pain away from what Rikki suffered but justice has been rightly served.
"We love you so much Rikki sleep tight little man you will always be in our hearts and never forgotten."
Rochelle has described the conviction a "victory" because "he thought he'd got away with it".
Rikki's sister Rochelle Neave, 30, remembered Rikki as "so loving, so caring" and said he "would sort us food out when parents wouldn't do it".
"He was cheeky," she said.
"He was so loving, so caring towards us. He would do anything. If there was no food in he would go to the shop, nick it, come back and feed us.
"He would make sure we were clean.
"He would run a bath. He was so clean, he loved being clean."
She said it was a "victory" that Watson had been found guilty of murder "because he thought he'd got away with it for that many years and thought we were just going to go away and roll under the table".
"We weren't," she added.
She said that when prosecutors felt there was insufficient evidence, she was part of a victim's right to review to get the decision reversed.
"We wrote a statement saying how we feel this cold case needs to be solved," said Rochelle.
She said she had felt "angry" when Watson had fled to Portugal, while on police bail, and shared photographs of himself in the sunshine.
"I thought 'if you're not guilty of murder, why would you run away'," she said.
Speaking of Rikki, Rochelle said: "I'm just so gutted that he's gone.
"I just imagine now, what would he have been like now.
"What would we all be doing now together, as we would all be together.
"It's what that would be like now which we didn't get a chance to do as someone took his life."
Clare Forsdike, a senior crown prosecutor at the CPS, said: "The conviction of James Watson for killing Rikki Neave concludes an appalling unsolved crime almost 30 years after it happened. It brings justice for Rikki.
"It has been like a jigsaw puzzle with each piece of evidence not enough by itself but when put together creating a clear and compelling picture of why James Watson had to be the killer.
"Ultimately a combination of evidence from DNA, post-mortem, soil samples, eyewitness testimony, and his changing accounts proved overwhelming.
"Only James Watson knows why he did it. He remained silent for two decades and then put Rikki's family through the agony of a trial.
"I hope the verdict gives some consolation to all those who love and miss Rikki Neave."
Watson will be sentenced at the Old Bailey on May 9.
