A British man who served 38 years in prison for murder had his conviction overturned on Tuesday after forensic evidence from the crime scene was tested and found not to match his DNA.

The man, Peter Sullivan, 68, is thought to be the victim of the country’s longest miscarriage of justice involving a living prisoner. The judgment follows the emergence of several other wrongful convictions in recent years, casting a shadow over the reputation of Britain’s criminal justice system and raising grave questions about the credibility of the appeals process.

Mr. Sullivan was imprisoned after the killing in August 1986 of Diane Sindall, 21, who suffered a frenzied sexual attack in Birkenhead, near Liverpool, as she made her way home from a pub where she also worked.

After DNA evidence was presented in the case, the Court of Appeal overturned Mr. Sullivan’s conviction.

“In the light of that evidence, it is impossible to regard the appellant’s conviction as safe,” said Timothy Holroyde, one of three judges presiding over the hearing. “We quash the conviction,” he added, ordering that Mr. Sullivan be released from custody.

Appearing via a video link from prison in Wakefield, West Yorkshire, Mr. Sullivan broke down in tears and held his hand over his mouth as he was told he would be freed, the BBC reported.