Theodore Wafer, dressed in jeans and a T-shirt, met officers outside his Dearborn Heights home after they responded to his 911 call around 4:30 a.m. on Nov. 2.
"What happened here?" Sgt. Rory McManmon asked, according to the recording played by prosecutors.
"A consistent knocking on the door, and I'm trying to look through the windows and the door," Wafer said. "It's banging somewhere else so I open up the door, kind of like who is this? And the gun discharged.
"I didn't know there was a round in there," Wafer told McManmon. "I don't get it. Who's knocking on your door at 4:30 in the morning? Bang, bang, bang — somebody wanting in."
Wafer, 55, is charged with second-degree murder in the death of Renisha McBride, who appeared on his porch 3 ½ hours after crashing her car a half-mile away in Detroit.
He told police that the victim, later identified as 19-year-old McBride, looked like a "neighbor girl or something." McBride didn't live in the neighborhood, and an autopsy revealed she was extremely drunk.
Wafer's lawyers say he shot McBride in self-defense. Prosecutors, however, say he should have called police if he feared for his safety.
Police asked Wafer about his weapon, which was on the ground in the foyer of his home when officers arrived.
"It's a little Mossberg, you know, shotgun. Self-defense," Wafer replied.
Copyright 2014 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.