Drew Whitley, 51, had been convicted of second-degree murder in 1989 for the shooting death of Noreen Malloy, 22, outside a McDonald's restaurant she managed.
Allegheny County District Attorney Stephen A. Zappala Jr. dropped the charges last May after DNA test results showed that hairs said to be from the killer did not match Whitley's.
The suit names six detectives, Allegheny County and one of Whitley's former attorneys.
Whitley was subject to malicious prosecution, was denied a fair trial and was targeted because he is black, the lawsuit claims.
Lawrence Fisher, Whitley's attorney, said Wednesday that justice was not fully served merely by exonerating Whitley.
"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," he said in an e-mail message.
The lawsuit claims detectives failed to test Whitley's 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.
They also ignored evidence clearing Whitley, including footprints in the snow at the scene that were smaller than his, a hat found at the scene that was smaller than his head and saliva on a ski mask that did not match his, according to the suit.
The suit also accuses Sanford A. Middleman, one of Whitley's attorneys after he was convicted, of professional negligence.
Middleman delayed taking any action on Whitley's behalf for more than two years and failed to pursue the most current DNA testing when he eventually requested a DNA test, the suit claims. He also allegedly failed to tell Whitley that the test yielded inconclusive results.
Police who responded to Malloy's shooting in August 1988 recovered a bloodstained coat, a hat and shoes outside the restaurant. The stocking mask was found in a parking lot nearby.
Blood on the shoes matched Whitley's blood type, but they were destroyed in a 1996 flood that wiped out much of a county police room used to store evidence.
A witness identified Whitley based on the shape of his face and his walk.
At the trial, a crime lab technician said 41 hairs found in the mask resembled Whitley's hair. DNA testing was not available at the time.
Two of the 41 hairs were damaged in a testing attempt in the 1990s and the other 39 were lost. They were found again in July 2005, and two months later a judge ordered that they be tested and compared to Whitley's DNA.
The results of that test favored the defense, and prosecutors asked that hairs from the hat be tested. Those tests came back showing that the hairs were not Whitley's.
Allegheny County police say the six detectives named in the lawsuit are no longer with the force.
One of the former detectives, Thomas M. Fitzgerald, said he had not seen the lawsuit and had no comment about it. Fitzgerald, currently a U.S. Marshal, said it had been years since he worked as a detective for the county.
Phone numbers for the five other ex-detectives could not immediately be found.
Fisher, the attorney, has said his client was "reconnecting with his family, appreciating his liberty and coping with the nightmares over the ordeals that he suffered."