A grand jury in Dallas County, Texas has exonerated two police officers who fatally shot an unarmed schizophrenic man last June.

Officers John Rogers and Andrew Hutchins responded to a request from the mother of Jason Harrison, 39, to help get her son to a hospital. She had made similar calls to the police many times previously.

On this occasion, the police fired repeatedly into Harrison after he failed to immediately heed their command to drop a screwdriver he was holding. Minutes after the mother had answered to door for the police, Harrison lay dead, shot five times, including twice in the back.

The release of a video last month from one of the officer’s body cameras brought the case back into the local headlines. The video shows Harrison’s mother answering the door, walking casually outside and saying, “Oh, he’s just off his chain. You can hear him talking about chopping up people.”

Asked of whom she is speaking by one of the cops, she replies, “My son, bipolar, schizo.” When Harrison appears at the door, twiddling a screwdriver between his fingers, one of the officers tells him to drop the tool. Five seconds later, the police shoot the man five times in rapid succession, while the mother cries out, “Oh, they killed my son!”

In their affidavits, the officers claimed they were forced to shoot the unarmed man after he failed to comply with repeated orders to drop the screwdriver.

The grand jury whitewash of this savage killing is only the latest in a series of high-profile police homicides in which the perpetrators have been exonerated despite clear video or eye witness evidence of murder. These include the killing of Michael Brown last August by Ferguson, Missouri officer Darren Wilson and the killing of Eric Garner last July by New York police officer Daniel Panteleo.