Depends on how murder is defined in the state's lawbooks.

In NH, there's Murder 1, meaning you planned to murder. Murder 2 means you had intent arising from immediate circumstance. Then you get into the 'manslaughter' defintions for things like crimes of passion (coming home, seeing your spouse in bed with someone else and going on a rampage) going down to accidents that shouldn't have happened (like vehicular manslaughter).

Everything I've heard from people with legal backgrounds seem to indicate that this is going to be some degree of a manslaughter case.