Editor's note: Police have released information saying Aura Rosser was only shot one time.

The boyfriend of the 40-year-old Ann Arbor woman who was shot and killed by police Sunday night said he doesn't understand why police had to use lethal force to take down the woman who had a knife in her hand as she confronted officers.

Victor Stephens, 54, is the homeowner at 2083 Winewood Ave., where his girlfriend was shot by police who were responding to a domestic disturbance call.

Victor Stephens

"Why would you kill her? He shot her in the head and in the chest," Stephens said. "It was a woman with a knife. It doesn't make any sense."

Stephens said the woman -- whose name is being withheld until police can reach the next of kin -- has three children, two sons and a daughter.

Police were called to the home at 11:45 p.m. Sunday night.

"Me and her, we had an argument. Glass was being broke, so I called the police to escort her out," Stephens said.

When officers arrived, Stephens said he was in a separate hallway in the house away from where the woman was with the knife. Stephens said the woman had a fish knife in her hand when police announced their arrival.

"The police said 'police,' so I stopped. She walked towards them," Stephens said. "They said 'freeze' and the next thing I know I heard (gunshots)."

After the shots were fired, Stephens later asked if he could talk to the woman and that's when he was informed she was dead.

"Where were the Tasers at? She wasn't going to kill anybody with a knife," Stephens said. "That's unnecessary."

Stephens said the hallway where the woman was shot was well lit, and it was clear the woman didn't have a gun. There were five people in the home when police arrived.

Stephens said he and the woman had been dating for about nine months and he believed she had a history of mental illness, but he wasn't able to elaborate. He said the woman had moved in with him so she could get away from Detroit and get some help in the Ann Arbor area.

Michigan State Police were conducting an investigation at the home Monday morning and have not released any details on what led the officer to shoot the woman other than to say she approached them with a knife. The investigation has been turned over to state police because an Ann Arbor officer was involved in the shooting.

Matt Durr covers Ypsilanti for The Ann Arbor News. Email him at mattdurr@mlive.com or follow him on Twitter.