I didn't see anything listed that had been stolen-wouldn't a burglar be grabbing/piling things to take to vehicle? They likely came across a computer or two, some electronics of value, etc, in all that time moseying around-and wouldn't someone who wanted to get in/get out grab some valuables move with a little more speed? Anything is possible, maybe they were just looking for something specific (box of cash/jewels, who knows?!?), and when they didn't find it they decided to spend a few minutes bludgeoning someone to death before leaving. Seems a bit extreme for someone breaking in with no specific goal in mind, imho.