Updated

A Richmond police officer who fatally shot a naked, unarmed man on an interstate highway will not face criminal charges because the shooting was "an act of justifiable homicide," a prosecutor said Friday.

In a report released Friday, Commonwealth's Attorney Michael Herring said the officer's use of deadly force in the death of Marcus-David Peters was "reasonable and necessary" given the unusual circumstances of his May 14 encounter with police.

Peters, a 24-year-old high school biology teacher, was shot and killed after he struck several cars with his vehicle, then emerged naked from his car and ran onto Interstate 95 during heavy rush-hour traffic.

Peters was struck by a car, but got up immediately, then laid back down on the road, rolled over in a tumbling motion and moved his arms and legs "as if making snow angels," the report said.

Peters was unarmed, but charged at the officer, who first fired a stun gun and then his service weapon.

Peters' sister, Princess Blanding, has said he was clearly having a mental health crisis and that police should have handled the encounter without lethal force. On Friday, she criticized Herring's decision to not seek charges against the officer.

"Michael Herring's decision to declare the killing of Marcus-David Peters a 'justifiable homicide' follows a chilling pattern for the city of Richmond, state of Virginia, and this nation to make public what we have known for hundreds of years: people with power value racist systems over Black and Brown lives," Blanding said in a statement for the family.

It added: "Elected officials, appointed officials and police departments will find every reason to refuse accountability and justify their violence against our communities."

Peters was black; Nyantakyi is also black.

In the report, Herring said Peters' death was tragic, but said his "erratic" and "aggressive" behavior was seen by officer Michael Nyantakyi "as a direct threat to his life and to the safety of those around him."

"A reasonable officer in this scenario would have believed that Peters was capable of overcoming the officer, taking control of the firearm and using it to harm the officer and others. Thus, the totality of the circumstances tragically warranted the use of lethal force," Herring wrote.

Herring said Nyantakyi called for backup and attempted to de-escalate the situation, but Peters became aggressive. Footage from the officer's body-worn camera shows Peters charging at the officer and threatening to kill him.

Herring noted that Peters' behavior was out of character for him. He was a highly regarded teacher and was working with his school on plans to develop a program for him to mentor at-risk teens.

Interviews with family members, friends and co-workers indicated that Peters began to behave erratically about a week or two before he was killed, according to Herring's report.

A toxicology report showed the presence of Tetrahydrocannabinol, known as THC, the main psychoactive ingredient in marijuana; and Ritalin, a stimulant used to treat attention deficit hyperactivity disorder and narcolepsy. The report said Peters did not have a prescription for Ritalin and that a witness acknowledged she gave him a bottle of generic Ritalin in the weeks before his death.

"I think it's clear now that Mr. Peters' decline began long before the day of his death," Herring said.

Herring said the officer backed away several times during his encounter with Peters and hoped using his stun gun would subdue Peters. But when that failed and Peters became more aggressive, the officer believed he had to fire his weapon, Herring said.

"The officer could not stand by while Mr. Peters continued to break down on Interstate 95," Herring said.

In the report, Herring said a relative of Peters admitted removing the Ritalin bottle from his apartment and disposing of it after his death. He declined to identify the family member.

The Richmond Police Department said now that Herring's review has been completed, its internal affairs unit will open an administrative investigation into Nyantakyi's actions to determine whether he complied with department policies.

Nyantakyi, a 10-year veteran of the force, has been on administrative leave during Herring's investigation. He will now be placed on an administrative assignment while the department's investigation is completed.

"This incident will forever remain a tragedy for all those involved," Police Chief Alfred Durham said in a statement.