Tests to establish the cause of death of a 15-year-old boy whose body was found in an alleyway have proved inconclusive, police said.
Officers were called to reports of a body discovered off Ripponden Road in Oldham, Greater Manchester, at 8am and his death remains unexplained.
Chief Superintendent Chris Sykes, from Greater Manchester Police, said there was nothing to suggest any wrong-doing at this stage but police "cannot rule out third party involvement".
He said: "A post mortem to find the cause of death was inconclusive therefore further toxicology tests are required and his death remains unexplained at this time.
"I would reiterate that while there is nothing to suggest any wrong doing, we cannot rule out any third party involvement so we are continuing to fully investigate the circumstances of what happened.
"We would urge anyone with information to get in touch as your information, however small and insignificant it may seem, could help us to piece together the movements of this young man on Friday night into Saturday morning.
"We have officers patrolling the area so would ask anyone who may have seen or heard anything suspicious in the area that night to speak to us."
Anyone with information should call police on 101 or the independent charity Crimestoppers anonymously on 0800 555 111.