A 44-year-old woman has been arrested on suspicion of murder of Jonathan Cairns 20 years ago.
The woman was arrested in Dungiven and was being questioned about the murder in April 1999.
The 18-year-old victim was attacked and killed as he made his way home from a night out in the early hours of Sunday April 25 1999.
His body was discovered in a shallow grave at Loughermore Forest close to his Ballykelly home. No-one has ever been convicted of the teenager’s murder although a 49-year-old man was sentenced to five years in prison in 2002 for perverting the course of justice.
Detective Inspector Adrian Brown appealed for people to "search their conscience" and come forward with information.
“I continue to appeal for information in relation to Jonathan’s murder. For over 20 years, Jonathan’s family and friends have suffered intolerable grief and they deserve answers. I understand their desire to see justice done and I believe that people within the Ballykelly community have information that could assist my investigation.
“Some people were not prepared to come forward at the time for a variety of reasons but I am 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.
"Anyone with information should call detectives on 101. Or, if someone would prefer to provide information without giving their details, they can contact the independent charity Crimestoppers and speak to them anonymously on 0800 555 111.”
In April, Mr Cairn's father marked the 20th anniversary of his son's murder by making an emotional appeal for information. Raymond Cairns said his family has spent 20 years living without their "lovely son" and living without answers or 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," Mr Cairns said.
More than 20 searches have been carried out in the last 20 years. Police have identified more than 2,500 witnesses in the case and taken almost 900 statements.
Police believe Mr Cairn's killers were local to the area and may even have known their victim.
