More than 2,500 witnesses have been identified as part of the police investigation into the murder of a teenager in Co Londonderry.

Jonathan Cairns, 18 and from Ballykelly, was attacked and beaten to death as he made his way home from a night out in the early hours of April 25, 1999.

His body was found in a shallow grave in Loughermore Forest, not far from his home, later that day. His bloodstained clothes were also discovered in the grounds of Glasvey Special School.

One man was jailed for perverting the course of justice, but no one has been convicted of murder.

Detectives have conducted searches in the area to mark the 20th anniversary and officers handed out leaflets.

Mr Cairns’ father Raymond said: “Today I am making this appeal as it’s been 20 years since our son was murdered.

“20 years of living each day without our lovely son, 20 years of living without answers, and without justice.

“Jonathan was 18 when he died, he should now be 38 – maybe with kids of his own.  We think about him every day. He was always smiling, always happy.

“The people who did this took our son away from us and we don’t know why.  All of his family loved him and miss him so much. To anyone who has information, it’s never too late to come forward. Please tell us what you know.”

The investigation into the murder has involved:

– The identification of more than 2,500 witnesses

– Taking statements from 872 people

– More than 20 searches.

Leading the investigation, detective inspector Adrian Brown said: “For 20 years, Jonathan’s family and friends have suffered intolerable grief.

“Their son died a violent death as a result of a vicious beating and we understand their desire to see justice done.

“We are committed to doing all in our power to apprehend those involved in this brutal incident which went far beyond a drunken assault.”

He said the killer or killers were local to the area and may have known their victim.

He added: “I also believe that people within the Ballykelly community have information which could help solve this case.”

A mobile police station will also be open today until 7pm in Ballykelly village.

The detective added; “Two men were seen in the area where Jonathan was assaulted on the Loughermore Road in the early hours of Sunday 25 April 1999.

“They have never come forward to speak to police despite numerous appeals which leads me to believe they were involved in the murder.”

He added: “Some people were not prepared to come forward at the time for a variety of reasons but we are asking people to search their conscience and think again.

“Circumstances and loyalties may have changed over years and it is never too late to do the right thing.”

He appealed for people to contact police directly or give information to the Crimestoppers charity.