The death of Dungannon teenager Matthew McCallan is no longer being treated as unexplained, police have said.
Detective Inspector Michael Winters was speaking following the results of a post mortem.
He also said that while detectives are not treating the death of the 15-year-old as suspicious, they are “still trying to determine the circumstances” leading up to it.
Matthew’s body was found in a ditch in the Tattyreagh Road area of Fintona shortly before noon last Monday, after he failed to return home following a night out at a country music festival on Saturday.
The funeral of the St Patrick’s College, Dungannon, pupil took place on Sunday at St Malachy’s Church in Edendork.
In a statement, police said detectives in the Criminal Investigation Department are continuing to investigate the circumstances surrounding the schoolboy’s death.
Detective Inspector Winters said: “Our thoughts remain with Matthew’s devastated family at this time and we are trying to provide these answers for them.
“A number of specially trained officers are continuing to provide support to them at this tragic time.
“I am keen to hear from anyone who has CCTV in a number of areas within Fintona, including Loughmuck Road, Edergole Road, Tullycunny Road, Blackfort Road and Tattyreagh Road.
“I would appeal to anyone who has CCTV in these areas and hasn’t yet spoken to police to come forward.
“I am also appealing for anyone who was driving on these roads between 1am and 5am on Sunday, December 4 and who were using dashcam, to speak to police.”
He added: “Matthew was last seen at approximately 1.20am near the Ecclesville Centre, Fintona, and we are keen to establish his movements after this time.
“Police received a report of a missing person shortly after 3.30am on Sunday, December 4 when Matthew did not arrive home after attending an event in Fintona on Saturday night.
“Sadly, Matthew was discovered by a member of the public in a ditch in the laneway of a property approximately two miles away from the social event at around 11.45am on Monday, December 5.
“I would appeal to anyone who saw Matthew or anyone who has CCTV or dashcam footage, to contact police on 101, quoting 319 of 04/12/22.”
The case has been referred to the Police Ombudsman following concerns expressed by the family about the PSNI response.
Matthew’s mother Frances has claimed the police were slow to act and that she had told them her son’s disappearance was “totally out of character”.