Crown prosecutors aimed to undermine claims that an intruder killed teenager Billie-Jo Jenkins at the Old Bailey yesterday.

The prosecution in the Sion Jenkins murder retrial instead asserted that blood spots found on his and Billie-Jo's clothes proved Jenkins had killed her.

Prosecuting counsel Nicholas Hilliard suggested that the spots spattered on to their clothes as Jenkins struck Billie-Jo forcefully with an iron bar.

He said nobody else who had come into contact with Billie-Jo had blood spots on them like Jenkins, including paramedics who had moved her around more than him.

Mr Hilliard said the jury would, in due course, be asked to consider whether a blockage in Billie-Jo's upper airway led to an exhalation of blood to account for the spatter as he tended her in her dying moments.

However, Mr Hilliard said: "The prosecution suggests that the blood found on the defendant was as a result of impact spatter."

He added that the jury would be asked to consider whether an intruder was responsible for murdering Billie-Jo and their attention was drawn to a mentally ill man named Mr B.

A number of people saw him with a carrier bag and a French loaf at around 2.30pm on February 15, 1997, in a park close to the Jenkins' home.

That same afternoon 13-year-old Billie-Jo was murdered as she painted patio doors at the Jenkins' three storey Victorian home in Lower Park Road, Hastings, just minutes away from the park.

In the months before, the jury heard there had been reports of an attempted break-in at the house plus attacks on their cars and odd phone calls.

In addition there were claims that Billie-Jo herself had complained of being followed.

Yesterday, Mr Hilliard played down the significance of the mysterious Mr B on day two of the retrial.

He said Mr B was arrested a couple of days after the killing but that none of his clothes had Billie-Jo's blood or paint on them.

One of the striking features of Billie-Jo's death was that part of a plastic bag had been stuffed deeply into one of her nostrils.

On his arrest, Mr B was seen to put a piece of plastic to his face and produce some from his trousers.

Yet Mr Hilliard said there was nothing to firmly place him as a prime suspect in Billie-Jo's murder.

He said: "In his disturbed mental state Mr B didn't leave any trace of him being the killer.

"And if he was the prowler in the months before, it seems he escaped detection then too."

Mr Hilliard said the basis for Mr B being implicated was his bizarre obsession with plastic.

The Crown claim 47-year-old Jenkins, former head teacher designate at all boys William Parker School in Parkstone Road, Hastings, battered Billie-Jo at least five times with a metal bar in a fit of rage.

Moments later, it is alleged, he took his two natural daughters Lottie and Annie on a contrived journey in his car to a Do It All store to buy some white spirit before returning to pretend to find Billie-Jo's body.

Jenkins denies murder. The trial continues.