Schoolgirl Billie-Jo Jenkins' death would have been virtually instantaneous, the Old Bailey heard yesterday.

Pathologist Dr Nathaniel Carey told the jury the 13-year-old's scalp had been hit so hard that it had split.

He gave evidence yesterday at the retrial of her foster father Sion Jenkins as he stands accused for a second time of her murder.

Jenkins, 47, ex-headteacher designate at the William Parker School for boys in Parkstone Road, Hastings, is alleged to have battered her to death with a metal tent spike.

Billie-Jo, who attended Helenswood School on The Ridge, St Leonards, was painting patio doors at the family home in Lower Park Road, Hastings, when she was killed on February 15, 1997.

Dr Carey said it would not be surprising if particles of the teenager's skin had broken off and flown through the air in tiny drops of blood.

The prosecution alleges that three blood spots found on the lower right leg of Jenkins' trousers contained flesh.

Four similar spots on Billie-Jo's leggings also had flesh inside, the jury was told.

Dr Carey said the white particles which turned out to be skin cells were among tiny deposits of blood.

Asked whether they could have come from the severe wounds on her head, the pathologist said he thought it "entirely possible and plausible. It is the most likely origin".

Dr Carey was asked how long Billie-Jo would have survived.

He replied: "It would be virtually instantaneous death. You would die very rapidly from that type of head injury. She could have survived several minutes - albeit in a deeply unconscious state."

Jenkins was convicted of Billie-Jo's murder at Lewes Crown Court in 1998 and jailed for life.

However, his conviction was quashed at the second attempt by three appeal court judges last July and a retrial was ordered.

Jenkins denies murder and the case continues.