The family of a Londonderry man who died after going missing from hospital on Halloween night say questions about his death must be answered.
Harry Jack was buried on Tuesday
A woman told the BBC that she had seen Harry Jack, 44, in his pyjamas leaving Altnagelvin Hospital, where he was being treated for a fractured skull.
She said she contacted the hospital and asked them to pass her mobile number to the police, but no-one rang her back.
Mr Jack's brother-in-law said his life could easily have been saved.
Kenny Nixon said a basic set of steps would have made all the difference after he went missing on 31 October.
"One person makes a phone call, to an authority such as the hospital, who passes this information on to the police," he said.
"The police (would) take this woman's phone number and contact her.
"All the police had to do was approach this woman's car and Harry was within 50 yards - you would have found him in less than two minutes."
Mr Jack was treated for a fractured skull at Altnagelvin Hospital
Mr Jack's body was not found until three days after he went missing. His funeral took place on Tuesday morning.
The Police Ombudsman's office have confirmed they are investigating the case.
Foyle MP and SDLP leader Mark Durkan has tabled a parliamentary question urging the secretary of state, Peter Hain, to order an inquiry into the incident.
"Clearly, there needs to be a full and proper report into what happened and how it happened," he said.
"Harry Jack's family have many questions they want to ask - and to which they have every right to get answers."
On Monday, Yvonne Porter, who followed Mr Jack after spotting him, told the BBC she had contacted the hospital three times and asked for her mobile number to be passed on to police, but no-one phoned her back.
A hospital spokesperson confirmed they had received two calls from the same person about Mr Jack on Tuesday evening and passed the information to police.
The spokesperson could not confirm whether a third call had been received or whether the caller's phone number had been given to the police.
The police said they were told Mr Jack was missing shortly before 2000 GMT last Tuesday.
They said a patrol had searched the Daly's Brae area where he was reported as being spotted within 20 minutes but were unable to find him. They said that they also searched the grounds of the hospital.