Post-mortem examination into teenager Caolan Page's death
A post-mortem examination on the body of County Donegal teenager Caolan Page is due to be carried out on Tuesday morning.
The 19-year-old from Upper Kildrum in Carrigans was discovered in Magazine Street, Londonderry, early on Saturday morning.
He had serious head injuries and was taken to Altnagelvin Hospital, where he died later.
Police are examining CCTV footage to try to establish what happened to him.
Mr Page was an A-level student at St Columb's College in Derry and had wanted to become a vet.
It is understood he had gone out with friends on Friday night and had become separated from them. It is possible that he was attacked or that he fell from the city walls.
Police said they had obtained CCTV images from the surrounding area and were studying footage to determine what happened.
"Detectives are still very interested in talking to anyone who may have information about the incident," a police spokesman said.
"Police are particularly keen to speak to people who saw a man collapse in Magazine Street around 02:00 BST on Saturday or who were in the Waterloo Place area around the same time or who came into contact with Caolan."