A TEENAGER was today found guilty of murdering a female prison officer and sentenced to a minimum term of 20 years jail before he is eligible for release.

Matthew Doman suffocated 30-year-old Naomi Phipps with a plastic bag and battered her head causing a brain injury.

Judge Alistair McCreath said the killing was sexually motivated after police found DNA traces on the victim's bed.

Doman, aged 19, showed no emotion as the judge passed a mandatory life sentence. He will only be freed when the Parole Board consider him safe.

He went to the home of Miss Phipps - his next door neighbour - in Patch Lane, Oakenshaw, after drinking more than 10 pints of lager.

He also boasted to pals that he was "pilled up" by taking ecstasy tablets.

After killing the Blakenhurst prison employee on October 22 last year, Doman combed and arranged her hair on the bed sheets, Worcester Crown Court heard.

The judge said that was a particularly "chilling" aspect of the case and was not consistent with remorse because Doman then stole the victim's wine, cigarettes, mobile phones and car.

A skilled liar, Doman invented a story that Miss Phipps had died accidentally during a biazarre practice to restrict breathing and intensify love-making.

The judge said it had been distressing for her family to listen in court to her name being besmirched.

The depleted jury of five men and five women came to a unanimous verdict on day seven of the trial after retiring for six hours.

One juror was dismissed by the judge after talking about the case at work. Another became ill with a viral infection and had to be taken to hospital.

Doman dumped the victim's car and then stayed with friends in Redditch before being persuaded to surrender to police.

He lied that he had taken a train to Devon and that he had killed Miss Phipps by hurling a computer tower at her during a row.

He later changed his story to a sexual encounter which went wrong.

But prosecutor Robert Juckes QC revealed that she was gay and had no intimate interest in men.

Miss Phipps had been friendly with Doman until he supplied her with drugs - and then tipped off police, the jury heard.

They found cocaine in her home and she was suspended from her job. She was facing a work tribunal the day after her death.

Minutes before she died, she emailed a friend telling her she would like to "kick the head in" of the boy next door.

After the verdict, Mr Juckes told the jury that Doman - who refused to finish his evidence under cross-examination - had a record going back to 2002 which included possession of a knife, battery and making threats to kill.

He suggested the motive for the murder may have been Doman's fear that Miss Phipps was going to reveal him as her drug supplier.

Stephen Linehan QC, defending, said there would always be uncertainty over what happened before her death, but she died quickly.

Det Chief Insp Dave Morgan, of West Mercia Police, said: "My first thoughts are with Naomi's family, in particular her parents, David and Jenny, and brother Nick, who have lost a much-loved daughter and sister.

"Hopefully the sentence will ease their pain a little, knowing that the man responsible has been brought to justice.

"The circumstances of the case have been disturbing. The violent nature of Naomi's death has been a shock to her family and friends and to the Redditch community."