A complex relationship, a vicious crime, an unknown motive. BBC Correspondent Peter Gould reports.

The jury of eight men and four women at Lewes Crown Court decided by a unanimous verdict that Jenkins, a man with no previous convictions, was guilty of the brutal murder.

Mr Justice Gage, sentencing Jenkins to life, told him he was a danger to the community. The judge told the defendant: "Sion Jenkins, the jury have convicted you of murder in what my judgement was compelling evidence.

Peter Gould at Lewes Crown Court: "The motive is only known to Sion Jenkins"

"On the 15th February last year you battered your foster daughter with an iron bar.

"It was a furious assault, the motive for which only you now know."

Passing sentence the judge said: "By any standards this is an horrendous crime.

"The fact that you committed this crime, the circumstances in which it was committed and the way in which it was committed lead me to conclude that you are a very considerable danger to the community.

"There is only one sentence. You will be sentenced to the equivalent of life."

Officers were appalled at the brutality of Billie Jo's murder

As the foreman announced the verdict there were shouts of "Yes" from the packed public gallery where Billie-Jo's natural father and mother Bill and Debbie Jenkins sat.
The verdict on the 20th day of the trial came after the jury had been out for 10 hours 40 minutes.

Jenkins' lawyers are planning to appeal against the verdict.

'Killed in a fit of rage'

Deputy headmaster Jenkins, 40, had denied murdering 13-year-old Billie-Jo as she painted the patio doors at the family home in Hastings, east Sussex, on February 15 1997.

He had claimed that he had returned from a shopping trip with two of his natural children to discover her body.

But the jury found that he had killed her in a fit of rage and used an aborted shopping trip as cover.

Sion Jenkins was arrested one month after the murder

The 19-day trial heard testimony from 15 witnesses including Jenkins himself. He said that he did not know who killed Billie-Jo, and admitted that he was confused at the time of attack.

He claimed that blood on his clothes came from a bubble bursting in Billie-Jo's nose as he attended to her.

A paediatrician called the defence impossible. Another paediatrician said the distribution of blood was consistent with the wearer of the clothes delivering several blows to the head.