Police said Jonathan Neill (34) handed himself over to the Prison Service on Tuesday afternoon.

When he was 16, he was convicted of murdering a man who was lodging at his family's London home in 1991.

Neill stabbed Donald McKenzie 24 times while he was asleep in bed.

After killing him, Neill carved a cross and the numbers 666 into the victim's back.

The court noted at the time that the only explanation ever given was that he "wanted to know what it felt like to kill someone".

Before 1991, Neill had eight previous convictions for burglary and criminal damage. All of theose crimes were carried out in Northern Ireland.

He was released from prison in 2006, but was quickly returned to prison after breaching the terms of his licence.

However, since then he was said to have made progress and was staying in a hostel in the Cookstown area.

Max Murray, head of operations at the NI Prison Service, said they did not believe Neill presented an immediate danger.

"We would agree with the police advice that the public should not approach him," he added.