TULSA, Okla. - An unarmed black man who was fatally shot by police in Oklahoma last month while he had his hands in the air had a hallucinogenic drug in his system when he was killed, according to an autopsy released on Tuesday.

The shooting of Terence Crutcher , 40, was one in a string of police killings of unarmed black people over the past two years that have sparked protests and debate across the United States . Tulsa police officer Betty Shelby has pleaded not guilty to first-degree manslaughter in connection with the shooting and is out on bond.

The Oklahoma Medical Examiners Office report said Crutcher had 96 nanograms per milliliter of phencyclidine, or PCP, in his bloodstream at the time of his death on Sept. 16. The office said the figure reached the threshold for acute phencyclidine intoxication.

Tulsa police said previously that PCP was discovered in Crutchers stalled SUV after his death. Police said Crutcher was unarmed and had no weapon on him or in his car. The department also released video of the shooting that showed Crutcher had his hands in the air and was in clear view before he was shot.

American Civil Liberties Union of Oklahomas executive director, Ryan Kiesel, said Crutcher having drugs in his system was irrelevant to his killing.

Drug possession and drug use do not now, nor should they ever, justify summary execution, he said, adding that the findings do not tell us whether or not Terence Crutcher was under the influence of PCP at the time of this encounter. Testing positive to a substance in your system is very different than being under the influence of a substance.

According to an arrest affidavit, the officer overreacted when she came upon Crutcher, whose car had broken down. Shelby has said she fired her weapon because she feared for her life.

Under Oklahoma law, first-degree manslaughter carries a minimum sentence of four years. She is scheduled to appear in court for a preliminary hearing on Nov. 29.

PCP, initially developed as a human anesthetic in 1959, is an illegal drug that can produce a dissociative mental state in users as well as delirium, confusion and other effects, according to the U.S. National Library of Medicine.

(Reporting by Lenzy Krehbiel-Burton in Tulsa, Okla.; Editing by Curtis Skinner and Peter Cooney)