Updated

A suspended Las Vegas police officer accused of using an unapproved chokehold on an unarmed man he was trying to arrest became the first in the department in 27 years to be charged with involuntary manslaughter.

Officer Kenneth Lopera's on-duty actions in the May 14 death of Tashii S. Brown outside a Las Vegas Strip casino amounted to criminal conduct, Clark County District Attorney Steve Wolfson said Monday. The prosecutor also filed a charge of oppression under color of office against the 31-year-old officer.

"The bottom line is, a police officer who crosses the line and commits crimes should be charged," Wolfson said.

The filing had been expected after police arrested Lopera a week ago. He posted $6,000 bail and was freed pending arraignment Aug. 21.

Lopera remains suspended without pay and could face up to eight years in state prison if he's convicted of both charges.

The Clark County coroner said Brown was intoxicated by methamphetamine and had an enlarged heart. But he died from lack of oxygen, or "asphyxia due to police restraint." His death was ruled a homicide.

Three Las Vegas police officers were indicted on involuntary manslaughter and oppression charges following the July 1990 chokehold death of 39-year-old Charles Bush. Their trial ended when a jury deadlocked, and they were not retried.

Lopera's police union legal representative, Steve Grammas, said Lopera will plead not guilty and fight the charges against him.

Police officials say Lopera violated several departmental policies when he chased Brown out a rear entrance at The Venetian, zapped him with a stun gun seven times, punched him more than 10 times and put him in the chokehold for a minute and 13 seconds.

Lopera is heard on body camera audio describing the arm-around-the-neck restraint as a "rear naked choke."

The chase began when a sweaty and agitated Brown approached Lopera and his patrol partner in a casino coffee shop, said he thought people were after him, and ran down employees-only hallways.