Detectives have reopened the investigation into the murder of a teenager found dead in a shallow grave after new lines of inquiry emerged.
Jonathan Cairns, 18, was assaulted on his way home after a night out in Ballykelly, Co Derry, on April 25, 1999.
His body was found in Loughermore Forest, five miles outside the village.
One man was jailed for perverting the course of justice but no one has been convicted of Mr Cairns' murder.
Police said a number of new lines of inquiry emerged during a review of the cold case.
The officer in charge of the reinvestigation, Detective Chief Inspector John McVea, said he was committed to pursuing all those involved and bringing them before the courts.
He said he believed the killers lived locally and inquiries would be conducted in the village over the coming days.
"We are following a number of new lines of inquiry and are keen to speak with anyone who may be able to assist us with the investigation," he said.
"Jonathan was a local teenager who was killed on his way home after a night out. We believe his killer or killers also lived locally. We also believe that people within the Ballykelly community have information which could help solve this case.
"We appreciate it is almost 13 years ago but we are asking people to think back to the Saturday night and Sunday morning of 24/25 April 1999.
"Police spoke to many people at the time but we are still trying to identify anyone who was in the Clooney Road/Loughermore Road/Caman Park areas of Ballykelly between 1.30am and 9am on Sunday 25 April.
"People may not have been prepared to come forward at the time for a variety of reasons but we are asking local people to think again.
"Circumstances and loyalties may have changed over the intervening 13 years and it is never too late to do the right thing."
Detectives can be contacted at North Queen Street in Belfast on 028 9056 1812 or anonymously through the independent charity Crimestoppers on 0800 555 111.