Probably tracks, blood puddles, and bullet trajectories. When Josh was doing a walk-through with the detective he talked about it. Unless I’ve got it confused (possible!), I’m pretty sure the detective said Olga was shot first as she was unlocking the door. Joey was shot but managed to take off and tripped over a guy wire, which is when they bludgeoned him before finishing him off with more shots. That’s how Joey ended up next to the building. I think I’ve still got it. I’ll rewatch it tomorrow as I’m curious. Edited to say I would normally understand running after being shot, but with this guy and his nutty mommy I had to laugh.