Norfolk prosecutors have told a former death row inmate convicted in the 1979 murders of a mother and daughter that all biological evidence in his case was destroyed years ago, making it impossible for him to seek DNA testing.

Joe Giarratano's case came into the national spotlight in the 1990s, when doubt emerged over whether he killed a 44-year-old Norfolk woman and raped and strangled her 15-year-old daughter. Questions about the case prompted then-Gov. L. Douglas Wilder (D) in 1991 to grant Giarratano a conditional pardon that allowed him to avoid the electric chair. He remains in prison.

Giarratano's attorney Barry Weinstein said he is disappointed that no evidence was found but will continue to pursue the case. "We are not taking this as a finality," Weinstein said. "A 'no' is not enough. I would like to know when it was destroyed, why it was destroyed and under whose authority it was destroyed."

Last month, Weinstein asked Norfolk authorities to search for any samples of blood, semen or hair that had been preserved in the case. Giarratano's attorneys had hoped to submit the evidence for complex DNA testing that was not available in the 1970s.

Norfolk Commonwealth's Attorney John R. Doyle said he has reviewed Giarratano's case and is confident of his guilt. He said the only biological evidence that remains is blood samples from the victims.

"I wish that this evidence did exist," Doyle said. "At some point, when they thought there would be no more need for future tests, it was destroyed."

Virginia legislators last year approved a law that allows inmates to present DNA evidence that could exonerate them long after their convictions. The state's tough evidence laws allow inmates only 21 days after sentencing to present other types of newly discovered evidence, including fingerprints, new witnesses and recanted testimony. The Virginia Supreme Court is considering loosening that provision.