PITTSBURGH — A man freed from prison after 18 years when DNA evidence failed to link him to a 1988 murder sued police yesterday claiming they violated his civil rights.

Drew Whitley, 51, had been convicted of second-degree murder in 1989 and sentenced to life in prison for the shooting death of Noreen Malloy, 22, outside a McDonald’s restaurant she managed in Duquesne, about 13 miles southeast of Pittsburgh.

A witness had identified Mr. Whitley based on the shape of his face and his walk, and a crime lab technician had said 41 hairs found in a mask at the scene resembled Mr. Whitley’s hair. DNA testing wasn’t available at the time.

New DNA tests ordered in 2005 indicated that the hairs believed to be the killer’s did not match Mr. Whitley. Allegheny County District Attorney Stephen Zappala Jr. dropped the charges last May, and Mr. Whitley was released.

The lawsuit names six Allegheny County detectives, the county and one of Mr. Whitley’s former attorneys. It claims Mr. Whitley was subject to malicious prosecution and denied a fair trial because he is black.

It also claims detectives failed to test his hands for gunshot residue, failed to administer a lie-detector test, and ignored his assertions that he had nothing to do with Malloy’s death. Evidence that could have cleared Mr. Whitley, including footprints in the snow, a hat, and saliva on the mask, was ignored, according to the lawsuit.

“We must hold accountable those responsible for the violation of his civil rights, the malicious prosecution by which those rights were violated, and the flawed legal counsel that allowed it all to happen,” his lawyer, Lawrence Fisher, said in an e-mail.

The hair samples used in the case have also been an issue. Some were destroyed during testing in the 1990s, and the others were thought to have been lost until Mr. Zappala notified Mr. Whitley’s attorneys in 2005 that they had been found in storage.

The lawsuit accuses one of Mr. Whitley’s former attorneys, Sanford Middleman, of professional negligence, claiming he delayed taking action on Mr. Whitley’s behalf for more than two years, failed to pursue the most current DNA testing, and failed to tell Mr. Whitley the test yielded inconclusive results.

Mr. Middleman did not immediately return a phone call yesterday.

Allegheny County police say the six detectives named in the lawsuit are no longer with the force.

One of the former detectives, Thomas Fitzgerald, now a U.S. Marshal, said he had not seen the lawsuit and had no comment about it. Phone numbers for the others could not immediately be found.

Mr. Fisher, Mr. Whitley’s attorney, has said his client was “reconnecting with his family, appreciating his liberty, and coping with the nightmares over the ordeals that he suffered.”