The Robbinsdale police officer who shot and injured a teen earlier this year won't face any internal discipline or criminal charges.

The Hennepin County Sheriff's Office finished investigating the April 16 incident and an internal administrative review of the county's report concluded Thursday that Sgt. Thomas Rothfork "acted appropriately." The police department added that Rothfork followed its use-of-force policies when he shot 18-year-old Tania Harris after she came "charging" at the officers with a knife.

The department has also released a couple of images from the squad car video that show Harris running toward Rothfork with the knife.

"The officer felt his life was in danger," Police Chief Jim Franzen said Friday.

Harris' family has called the shooting excessive and said that she had the 8-inch knife because she was defending herself from people threatening her. The incident spurred a rally by Black Lives Matter Minneapolis, pushing for police to be prosecuted.

"I guess I'm not surprised by it," attorney Stephen Smith, who represents Harris, said about the police findings. "I do think there is some room here to question whether the officer needed to use lethal force. … Did he have to fire his weapon at her in order to get her to stop?"

According to the criminal complaint, officers responded to a call of a fight and saw Harris "burst" outside, chasing a woman with the knife and screaming that she was going to kill her. The complaint, which charged Harris with second-degree assault, said officers ordered her to stop and drop the knife; when she didn't, Rothfork fired twice 5 to 10 feet away, wounding her.

The sheriff's office investigated the incident, and didn't see any possible criminal actions by Rothfork, Franzen said. And an internal review of the county's report found that Rothfork, who has returned to work, didn't violate policies.

"It's our determination, but it's based off the sheriff's office's investigation," he said.

The video and report can't be released, he added, until Harris' criminal case is resolved. A jury trial is scheduled for Sept. 21 for Harris, who has recovered physically but suffers psychological trauma, Smith said.

It's not unusual for police to be cleared after shootings. State statutes justify the use of deadly force by law enforcement to protect the officer or someone else from death or great bodily harm.

In Minnetonka, officers were cleared by a grand jury in a 2013 fatal shooting of a man with an empty revolver. The same result happened for officers in last year's fatal shooting of a couple who had a knife on Hwy. 212. A June 20 case in Eden Prairie, where an officer "accidentally discharged" a gun after chasing a fleeing motorcyclist, is still under investigation.

Kelly Smith • 612-673-4141