A university student died in hospital three days after he was found unconscious after a night out, an inquest has heard.
Alex Green, 22, had been out celebrating his birthday in Bath on 30 September 2017.
He was found at a bus stop in Westmoreland Road at 03:48 GMT.
Avon Coroners' Court heard he died in hospital three days later from head injuries, but it was not clear how the student had sustained them.
A detective said Mr Green, from East Molesey, Surrey, could have been hit by a vehicle, fallen or been injured after he was taken to hospital.
CCTV of his last movements shows him running and walking through the city in the early hours of the morning.
Det Con Christian Vogler, of Avon and Somerset Police, said the last footage of Mr Green walking was at 03:42.
He was found at the bus stop six minutes later by a group of students who did not know him.
Hit his head
The inquest heard a bus had passed the stop just two minutes earlier but there was no sign of Mr Green on the road.
"I honestly don't know what happened in those six minutes," Det Con Vogler said.
"All I can do is say that he definitely wasn't on that road when the bus passed by.
"In those six minutes, where Alex is not captured on CCTV, it is possible that he could have hit his head somewhere."
Mr Green was taken to the Royal United Hospital and later transferred to Southmead Hospital in Bristol, where he died.
The detective said he believed it was "most likely" that Mr Green had sustained a head injury after he was taken to hospital, unconnected with him being found at the bus stop.
He said paramedics and doctors who initially examined the student had checked him for head injuries.
Fallen from trolley
However, Det Con Vogler told the inquest it was also possible Mr Green could have been hit by a vehicle when he was not in range of CCTV cameras.
Dr Basil Purdue, a forensic pathologist, told the inquest that Mr Green had bruises on his legs and buttocks, as well as across his right foot.
He said he believed Mr Green's head injuries had been caused by him either falling backwards or being knocked backwards.
There was evidence that Mr Green had fallen from a trolley in hospital, but Dr Purdue said he would be "surprised" if his head injury had been caused by that.
The inquest continues.