Gavin McGuire, 55, repeatedly insisted he had never been in her home town of Greenock in his life.
A trial has heard how detectives questioned him about unsolved killings after he had been convicted of abducting, stripping and strangling another teenager, Mhairi Julyan, in Kilmarnock.
He was treated as a suspect in the Doyle investigation when he was taken from his prison cell to be questioned in Maryhill police office, the High Court in Edinburgh heard.
In the dock is John Docherty, 49, who denies stripping and strangling Elaine Doyle, 16, yards from her home in Ardgowan Street, Greenock in June 1986.
As part of Docherty's defence the jury has been given a list of 41 "possible suspects" which, it is claimed, may include the real culprit.
Defence QC Donald Findlay said he did not intend to directly accuse Mr McGuire of Elaine's murder but of all the 41 names on the list, he best fitted the profile.
The lawyer said: "What I will suggest is that, undoubtedly, you could have been the killer of Elaine Doyle.
Mr McGuire replied: "I know that is what everybody is saying, what the experts are saying. That is why they came to me."
Despite denying the murder of Mhairi Julyan at his trial, Mr McGuire admitted in court yesterday that he killed her "in a moment of madness."
But he told the jury over and over again: "I did not kill Elaine Doyle."
The trial continues.