A MAN who told ­detectives he had murdered Elaine Doyle - almost 25 years after she died - was suffering from severe mental health problems a trial heard.

A psychiatrist said that bi-polar Alexander Cannon had delusions of guilt.

But defence QC Donald Findlay suggested Mr Cannon might have had "a deep dark secret".

His name is on a list produced by defence lawyers in the trial of John Docherty, 49, who denies strangling 16-year-old Elaine near her Greenock home in June 1986.

The list of possible suspects might include the true killer, the High Court in Edinburgh has been told.

A number have been called to court during the last five weeks to deny responsibility.

But lawyers agreed not to ask Mr Cannon to give evidence because medics said the process would be too challenging and might make his condition worse.

Mr Cannon walked into Greenock Police Office in February 2011 and said he wanted to confess to killing Elaine.

Detective constable Kenneth Campbell said: "His speech was slurred and slow. His eyes were bloodshot and I had concerns about his health."

Mr Findlay asked why a self-confessed killer was not detained and Mr Campbell told him: "I didn't think he posed a risk."

The following day, Mr Cannon was back in hospital.

Docherty, of Dunoon, denies murder and has lodged a special defence of incrimination claiming the culprit might be among a list of 41 names.