A jury reached a swift and proper verdict in acquitting William J. Barnes of murdering a police officer who died 41 years after Barnes shot him.

Now, the parole board should move just as swiftly to release Barnes, 74, from prison.

Barnes has been behind bars without bail since August 2007. Even though he has been cleared of the murder charge, his attorney says it may be six months or more before he is released, due to a minor parole violation.

Barnes' continued confinement is an abuse of power and waste of expensive jail space.

Granted, Barnes is no angel. He was a lifelong petty criminal and thug when he shot rookie Philadelphia Police Officer Walter T. Barclay in 1966 during a botched burglary. The shooting paralyzed Barclay and ruined his quality of life. The impact on his family has been painful.

But Barnes has already served time for that crime. He was convicted of shooting Officer Barclay and completed 16 years of a 20-year sentence in prison before he was paroled.

In 2007, Officer Barclay died at age 64 from blood poisoning and a urinary-tract infection. Then-District Attorney Lynne Abraham charged Barnes with first-degree murder, saying the shooting 41 years earlier began a chain of events that led to the injuries that caused the police officer's death.

The argument in support of the murder charges against Barnes was always both a medical and legal stretch. The mere six hours the jury spent deliberating the testimony underscores that prosecutors did not have a strong case.

But the decision to keep Barnes behind bars before trial and after his acquittal is excessively punitive. Not to mention, it is unlikely Barnes would have even been charged with murder if the person he shot was not a cop. Abraham had a history of applying a separate justice system for police officers.

In this instance, the cost to keep Barnes in prison and prosecute him amounts to a giant waste of time and taxpayers' money. And an embarrassment to the District Attorney's Office.

Current District Attorney Seth Williams should have dropped the charges when he took office in January. But he claims the case had to proceed once the medical examiner ruled it a homicide.

Barnes continues to be held in prison because of a minor violation of his parole terms: He had a cell phone and car keys when he was arrested in 2007. He has been acquitted of the charges that led to that arrest.

Barnes should be credited for the nearly three years he served awaiting trial and released without further delay.