Robert Brown, 47, then asked to be allowed to leave the witness box when he also discovered his accuser, Brian Buckley, was serving a life sentence for murder.
Buckley was convicted of sexually assaulting and strangling a 25-year-old mother of two in Wrexham, Wales - a case defence QC Donald Findlay claimed bore some similarities to Elaine's murder.
Buckley had accused Mr Brown of the murder in 2008 following a TV programme about unsolved killings.
After hearing that, Mr Brown said: "I cannot believe it. It is the first I have heard of this." He then turned to judge Lord Stewart to ask: "Can I have a break?"
On trial is John Docherty, now of Dunoon. The 49-year-old, denies murder.
Elaine's naked body was found yards from her home in Ardgowan Street, Greenock, early in June 2, 1986.
In the early hours of that morning Mr Brown and Buckley had been prowling the streets in the area on a thieving expedition.
A couple of days later they came to blows and Buckley left Greenock.
The High Court in Edinburgh heard the two youths had met in Polmont Young Offenders' Institution earlier in 1986 where they were serving sentences.
Mr Brown, who now lives in London, told police in a statement in November 1986: "I really don't think Brian would commit a murder, although he is a bit of a nutcase."
Mr Findlay asked him yesterday : "As far as you know, was Mr Buckley ever in the vicinity of Ardgowan Street on the night of the murder?"
Mr Brown replied: "I don't know where he went."
Mr Findlay asked: "Did you know he blamed you for the murder?"
Mr Brown replied: "No".
The trial continues.