A jury was challenged today to decide two scenarios as to whether James Watson, now 40 but then 13, killed Rikki Neave.

Prosecutor John Price, QC, said there was a “substantial body" of evidence including DNA that pointed to Watson.

But Mr Price told an Old Bailey jury the critical question was whether the variety of evidence did indeed combine to incriminate Watson “for the simple reason that he is indeed the killer of Rikki Neave”.

Or, said Mr Price, alternatively Watson “may he be a hapless innocent victim of what would be the most extraordinary, implausible, and unfortunate set of coincidences.”.

The court also heard today that Rikki’s mother, Ruth, had been wrongly accused of his murder after a picture of Leonardo Da Vinci's Vitruvian Man was found at the family home.

Six-year-old Rikki's naked body was posed in a star shape in woods after he was strangled in November 1994, the Old Bailey heard.

Police investigating his murder found a book containing a picture of the famous drawing of Vitruvian Man at the house.

Mr Price said: "It was said, as indeed is the case, that in one of its forms, the posture of the image resembles the way her son's naked body had been posed by his killer."

Ms Neave went on to be accused of killing him at the house and transferring the body in a buggy to the woods before reporting him missing, jurors heard.

But Mr Price told jurors sightings that day showed she could not have done it and she was acquitted after a trial.

The case remained unsolved for more than 20 years until a DNA breakthrough shed new light.

DNA belonging to child witness James Watson was identified on Rikki's trousers, which were among a bundle of clothes dumped in a bin near the woods.

In his statement in 1994, Watson, then 13, said he had skipped school and gone to the Welland Estate in Peterborough where his father lived on the day of Rikki's murder.

At around 12.30pm, he said he came across Rikki as he watched a digger in the road.

He told police he did not know the boy but recognised him from the estate.

According to his statement, Rikki said: "That's a big tractor, isn't it?" to which Watson replied: "It's not a tractor, it's a digger."

He told police Rikki walked away and he did not see him again.

In 2016, Watson allegedly changed his story the day before being told of the new DNA evidence.

He suggested he had picked Rikki up from behind under his armpits and held him up against a fence to look at the diggers.

Mr Price said the DNA added to a "substantial body" of evidence of other highly incriminating circumstances.

He told jurors that Watson allegedly asked his mother about a bogus radio report of a child killing, three days before Rikki went missing.

He allegedly asked if it was true that "a two-year-old boy had been abducted from the Paston area of Peterborough and he had been strangled and left naked off the Paston Parkway", and that the body was found by "the dyke".

Mr Price said: "If Watson invented such a report of child murder on Friday November 25,1994, what is one to make of the fact that only three days later, on the Monday, such a rare and terrible thing did happen in Peterborough?

"A local child did go missing. He wasn't aged two, he was six. But this child really was murdered. This child was strangled. His body was found just off the Paston Parkway. It was by the dyke. It was naked.

"And this real child had been with the inventor of this bogus radio report on the day he went missing. And, when they were seen together, they were about three minutes' walk from where his body was found."

Asked about it in 2016, Watson said he could not recall saying it.

After the murder, he also allegedly displayed an interest in the case, making copies of a front-page newspaper story.

Watson, now aged 40, of no fixed address, has denied Rikki's murder and the trial continues.