A Pennsylvania man who spent more than three decades behind bars for the rape and murder of a 15-year-old girl has been freed after a DNA test.

A judge voided 63-year-old Lewis Fogle's 1982 conviction on Thursday.

Fogle, who had denied shooting Deann Long in the head in 1976, told WPXI-TV upon release that he was looking forward to a steak dinner.

His tearful wife, Deb Fogle, who wed him three months before his conviction, was waiting for him outside court and said she always believed he would be cleared.

The Innocence Project, a group that works to exonerate wrongfully convicted people, had led calls for new DNA testing in the case.

It said sperm evidence had "excluded Fogle and pointed to an unidentified male".

"This has been an extremely long journey for Mr Fogle, who has always maintained his innocence of the 1976 crime," said David Loftis, of the Innocence Project.

District Attorney Patrick Dougherty conceded the conviction ought to be thrown out after agreeing to the new DNA test.

But he told Reuters news agency he does not believe Fogle is wholly innocent of involvement in Miss Long's death.

The prosecutor said he would decide by next month whether to retry Fogle. He has been released on a bail bond as he remains charged.

He was among four men arrested in 1981 after a mental patient identified them under hypnosis as suspects.

Fogle was convicted of second-degree murder based on the testimony of three jailhouse informants.

Charges against his three co-defendants were dropped for lack of evidence.

The district attorney said he would seek DNA from two of the other three men originally charged who are still alive.