The High Court in Edinburgh has heard of a long-running row since Elaine Doyle, 16, was found in a lane near her Greenock home more than 27 years ago.
The jury has been told that the strangled girl was covered with a blanket from a police car before being taken to the mortuary. It is not known who was responsible for that being done.
Yesterday retired detective inspector James Goldie, 76, vehemently denied he had covered Elaine's body.
"I am desperate to tell you I did not at any time cover the body," he said.
Mr Goldie also insisted that he had not ordered anyone else to cover Elaine.
Blankets were hung on a fence at the scene, the trial has heard.
Defence QC Donald Findlay described the action as "a humani-tarian thought".
But the lawyer added: "That was a potentially catastrophic blunder by police at the scene."
Mr Goldie replied: "I agree with you there."
Mr Findlay added: "It could have completely blown apart any chance there was of tracking down the real killer of Elaine Doyle."
Mr Goldie was shown statements he made during the long-running murder hunt.
In June 2012 he told detectives he was told that residents in a building were looking over the scene in Ardgowan Street. Two men were also approaching the scene in a lane.
Mr Goldie's state-ment added: "I told him - it was a young male officer, I don't remember his name - to go to tell the residents to move back into the house.
"He walked a few yards then turned to say he had some blankets in his panda car so I told him to take them and place them on the garden side to hide the view of the body."
Mr Findlay said the jury would hear "100% guaranteed gold-plated evidence" a blanket had covered the girl.
John Docherty, 49, of Dunoon, denies murder. He claims that at the time he is alleged to have stripped and strangled Elaine Doyle in a lane in Greenock he was at home with his parents, who are no longer alive.
The trial continues.