"Where's his reasonable belief that his life was in jeopardy or that he was in jeopardy of great bodily harm?" said lawyer Gerald Thurswell, who represents McBride's family.
It all comes down to what a jury thinks, Bretz said.
"You've got a gun. There's an unarmed young woman on your front porch," he said. "Is it reasonable to think that she's a threat to you? That's going to be a toughie.
"Is it fair to feel scared when a stranger is pounding on your door at 4 or 5 in the morning? Hell, yeah. ... Don't answer the door," Bretz said.
The shooting has drawn attention from civil rights groups who called for an investigation and believe race was a factor — McBride was black; Wafer is white.
Some drew comparisons with the case of Trayvon Martin, the black teen fatally shot last year in Florida. In that case, Neighborhood Watch volunteer George Zimmerman was acquitted of second-degree murder.
Bretz said both sides would be wise to stick to a "race-neutral" strategy. "Don't go there. Keep it on the facts," he said.
"Who wants to bring race into it? Everybody else. ... The defense doesn't want that. And the prosecution doesn't want to bring it in. I don't think they need to."
Wayne County Prosecutor Kym Worthy didn't appear to completely rule it out Friday.
"In this case, the charging decision has nothing whatever to do with the race of the parties," she said. "Whether it becomes relevant later on in the case, I don't know. I'm not clairvoyant."
The missing hours
McBride crashed her 2004 Ford Taurus into a parked car in Detroit, blocks away from Wafer's home, around 1:30 a.m., according to the Dearborn Heights police report.