So far testimony is showing the officers really failed to collect evidence at the scene and failed to safeguard it from contamination, not to mention some evidence went missing, some went unchecked for days and some was only turned over to the defense during the trial. In short there's plenty for the defense to appeal should this case go south.
The Detroit Free Press: Prosecution rests in Wafer trial, defense calls expert forensic pathologist
Curiously the prosecution is trying to keep plenty of evidence out, including the entirety of Mr. Wafer's statement to the police. They're only using a portion when he stated right after the incident that the shotgun went off accidentally, but there's a lot more that should be coming in. The judge denied the defense's oral motion regarding completeness for the whole statement to come in.
The accidental statement, coming shortly after the shooting while he was still shaken up is explainable as a distancing statement after the shooting. After all he was stuck in the back of a squad car for over an hour seeing her body after the shooting which will likely account for the "accident" statement. There's more in his full statement to the police that explains what happens and makes it look like a good self-defense case.
As always, Andrew Branca at Legal Insurrection is doing a nice job of covering the case.
At this point I'd say 2nd degree murder is not going to happen but there's still a chance for manslaughter. There's plenty of questions about that night, namely where McBride was for the three hour gap and if anyone was with here during the pounding on Wafer's house that are very much unanswered.