I have been reading up on this and it's pretty sad. This is not really a case of fan on fan violence. Apparently the victim was talking to (or hitting on) the murderer's wife in a bar.
The sad part is the victim was married and his wife was begging for motives or answers on Facebook before that latter part came to light.
If true you have to really feel for her. First you find out your husband was murdered, then you find out it was because he was talking to some other guy's wife who killed him in a jealous rage.
Looking at the killer's mug shot there was obviously a fight between the 2 guys.