A RETIRED detective was forced to look at a photograph of murdered Elaine Doyle lying on a mortuary slab - and threatened with prison for lying on oath.

The heated exchange came at the High Court in Edinburgh when defence QC Donald Findlay again accused Strathclyde Police of trying to cover up a botched investigation more than 27 years ago.

And a jury heard trial judge Lord Stewart warn John O'Neill, 61, that he would not be released from his duty as a witness pending further investigation.

The naked body of teenage Elaine was found in a lane near her Greenock home on June 2 1986.

Mr O'Neill - who retired in 2007 after 30 years' police service - was then one of the first detective constables on the scene.

Like other officers who have given evidence at the trial he was questioned at length about whether Elaine's body was covered with a police issue blanket.

In a statement in June 2012 Mr O'Neill told officers: "I do recall the idea being discussed at the locus that Elaine should be covered up to prevent people looking out of their tenements and seeing the deceased."

But in the witness box Mr O'Neill said he was not so sure. He claimed a later visit by officers last year had "sowed doubts in my mind".

Asked by advocate depute John Scullion, prosecuting, if he had seen Elaine covered with a blanket, Mr O'Neill replied: "I cannot remember that. I am just not sure any more."

Mr Findlay demanded to know "Who has ordered the cover-up and for what?"

Mr Findlay told the witness: "If you are lying about any of this, you cannot imagine what I will drop on your head from a great height."

Mr O'Neil was handed a book of photos and the lawyer said: "Look at it, a 16-year-old girl lying dead on a mortuary slab. Now tell me the truth. Have you no shame, sir?" "Of course I have," replied Mr O'Neill. But he continued to insist that - whatever he said in his earlier statement - he was confused.

John Docherty, 49, now of Dunoon, denies murder. The trial continues.