A PRISON worker is today facing a lengthy spell behind bars himself after being convicted of a string of serious sex crimes against girls.

John Cornwell will learn his fate next month when he returns to Teesside Crown Court to be sentenced - but was warned to expect jail.

The Darlington man, 53, was released on bail until his next appearance so probation workers can prepare background reports on him.

After being convicted of ten of the 13 charges he faced, Cornwell was told by Judge George Moorhouse: "These are very serious matters."

During a nine-day case, the jury heard how some of the allegations went as far back as the 1990s - but Cornwell disputed them all.

He suggested they were part of a vendetta and claimed one of his accusers deliberately encouraged the others to tell lies against him.

Two of the girls claimed he watched adult films in front of them.

Mr Cornwell, of West Auckland Road, admitted viewing hardcore pornography but said that was some time ago and when he was alone.

During the trial, he denied deliberately deleting the footage from his computer shortly before police seized his computer last May.

He told the jury that it must have been wiped off when he innocently installed software which was designed to speed up his machine.

The court heard that Cornwell twice dodged sex crimes investigations in the past when the girls were persuaded not to go to police.

Prosecutor Richard Bennett said the claims were supported by police discoveries at his home after complaints were finally made last March.

During a search of the property, pornographic videos were found which appeared to back up the claims the girls made.

Mr Bennett said matters resurfaced on New Year's Eve 2011, and official complaints were finally made to police several months later.

Cornwell, a support officer at Northallerton Prison and Young Offenders' Institution, was cleared of two sexual assaults and an indecent assault.

He was found guilty of four charges each of sexual assault and indecent assault, and two of engaging in sexual activity in the presence of a child.

The jury of seven men and five women spent a total of more than ten hours over three days deliberating on the charges.