I think it was more like 5-6 hunters he killed (IIRC it was 5 dead on the scene, one more passed away later). Actually, my girlfriend's brother-in-law was one of the first responders to the scene, and arrived to find his cousin gutshot and dying. Pretty messed up. From what I've heard, (at least) one guy was shot in the back, so I don't know how a self-defense defense is going to play out (I wouldn't be surprised if there may have been some taunting/threatening given that he was trespassing, but regardless I'd think self-defense is tough to claim when he shot people trying to flee). I don't know all the details, but from what I do know, it sounds like he's pretty guilty.
By the way, for those of you outside Wisconsin, re: this portion of the article:
State Attorney General Peg "The Keg" Lautenschlager is taking this case solely to (futilely) attempt to salvage a tanking career due to having recently gotten a DUI (driving under the influence) with a state-owned vehicle, which later brought to light the fact that she's damaged a total of three public cars thus far. Her image in the state is largely one of a useless degenerate alcoholic (IMO). The line about her prosecuting becase of a '"personal interest" in cases that involve crimes against people' is basically laughably ridiculous.