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 Peterborough home of his mother Ruth Neave.
Prosecutor John Price QC 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 said: “Ultimately the critical question for the jury in this case will be whether such a wide variety of evidence, including the DNA, just happens to combine to incriminate Watson for the simple reason that he is indeed the killer of Rikki Neave or whether, alternatively, may he be a hapless innocent victim of what would be the most extraordinary, implausible, and unfortunate set of coincidences.”
Watson, now aged 40, of no fixed address, has denied Rikki’s murder and the trial continues.