A FISCAL last night demanded a police explanation after a youth accused of assault walked free when the wrong witness was summoned to give evidence against him.

The case is the fourth this year in which serious errors have led to an accused escaping trial.

Scott Kennedy, 19, of Cartside Avenue, Johnstone, was set to stand trial accused of punching and kicking Paul Adams on the head and body, and attempting to strike him with a knife.

But when the Paul Adams who was cited by police was called at the start of the trial at Paisley Sheriff Court, it became clear he was not the alleged victim.

The 21-year-old electrician said later he believed he had been summoned in connection with an attempted break-in on his car last year.

The procurator-fiscal in Paisley has asked police for an explanation, the Crown Office confirmed. Last night, Strathclyde Police said: ''It would seem that a person of a similar name was cited for court in error. However, until further inquiries are made into the matter, it would be inappropriate to comment further.''

In three previous cases, all drugs-related, the accused walked free because of errors in search warrants. In March it emerged that the biggest forgery trial ever held in Scotland had almost collapsed before it began because of a typing error on a search warrant.

When depute fiscal Catherine White began to question Mr Adams yesterday, he denied he had been in Beith Road on July 30, insisted he had not been assaulted, and refused to accept he had given a statement to police.

Ms White, who had apparently been told the witness might prove unco-operative, asked if he was frightened to give evidence and warned him of the consequences of prevarication.

In a bid to show he had reported being assaulted and had given a statement, she produced the investigating officer's notebook, containing details of the alleged incident and asked him to identify his signature.

He asked if he could be allowed to explain his position and was told firmly to restrict himself to answering questions only.

When Mr Adams said the signature was not his and gave a date of birth which did not match that of the man who should have been standing in front of her, and defence solicitor Charlie McCusker expressed concerns about the manner in which the witness was being questioned, Ms White called for an adjournment to investigate the apparent error.

Minutes later, after apologising to Mr Adams and allowing him to leave, she explained to Sheriff David Pirrett that there had been a serious mix-up and Mr Kennedy was told that, in the circumstances, he would be acquitted.

As he finally left the court, a bemused Mr Adams explained why he had not suspected anything out of the ordinary after police went to his home to serve the witness citation on Friday night.

He said: ''Someone attempted to break into my car last summer. The locks were damaged. I assumed I had been called to court to give evidence about that.

''I never gave it a second thought until I stepped into the witness box and the fiscal began to give me a hard time. If she had let me show the court the citation, it might have shed some light on things.

''The first address given for the Paul Adams who should have been in court had been scored off and another address written in. It too had been scored off and my address written on the paper in blue ink.

''When she began to question me and warn me about perjury, I was completely shocked. It was as if she didn't believe me.

''As soon as I saw the signature on the police statement, I knew that I was in the clear.

''I don't know how this could possibly have happened, except that there is obviously someone else out there called Paul Adams.''