It sounds like the police were left with the choice of either shooting or retreating, unless they had some less lethal kind of weapon they could've used. It must've been a really bizarre and frightening experience for them to see a naked man approaching with a piece of broken glass. I think also that police in a small town like Mankato may be less prepared for this kind of thing than big city police, so they may have fewer alternatives.

I don't think it was the bipolar disorder or anything like that which caused the guy to do what he did - I think it was the drug (the methamphetamine). I've heard many stories of people doing very bizarre and violent things when under the influence of methamphetamine, and sometimes not even remembering what they did the next day. It seems to be a particularly dangerous drug in terms causing violent behavior, and I don't think it matters whether or not the person taking it had a diagnosable mental illness. I think it can affect anyone in very bad ways.