Who is this guy anyway?
He's just some guy that lived with his parents, and was into war games and reenactments for the most part. They haven't figure out why he shot the two SP's, but there is some scuttlebutt that he thought one of the pair was interested in his brother's wife.
That whole area is prime hunting and vacation location, so there are hunting cabins, a giant abandoned resort, etc.... that he could have run of. He also seems to have hidden caches of food, weapons, etc.... in the area.
They've been within a 100 yards of him, but they just can't grab him, nor are they willing to get into a fire fight with him.