Click to see Spoiler:
So what I think is happening is that the sheriff pulls up to the El Paso motel just as the Mexican "bad guys" are running for their lives. They don't seem to be carrying any money. Has the really bad guy arrived as they were attacking the "hero" and scared them away? Did the hero shoot at them before dying and the noise scared them away? The sheriff then returns to the scene of the crime in the motel, and at that point the really bad guy has clearly been there, as the lock has been blown out. I thought the sheriff could maybe even see the reflection of the bad guy in the lock, meaning the bad guy was inside. You also see the bad guy in a dark hotel room, with a circular ray of light coming in, as if through one of the blown out locks. So the impression you get it that the bad guy is in the room that the sheriff is outside of (although there are 2 adjoining motel rooms in the crime scene tapes, so maybe not). The sheriff opens the door and does NOT turn on the light, standing silloutted in the door frame for quite a while, backlit. Then he goes to the bathroom and turns on the lights. Then he comes back and sits on the bed and apparently sees that someone has used a coin to unscrew the AC vent--so presumably the hero hid the money there again, and since the bad guy figured t hat out from the vent scratch marks at the earlier motel presumably the bad guy has used the coins to open the vent and take the money. But the bad guy is not in the motel room.
So...was the bad guy in the other room for some reason? Maybe he looked for money in that room first and then went to the other room and found it? Or was he in that room behind the door and slipped out when the sheriff went into the bathroom?
My SO thinks the bad guy was in the adjoining room and that the sheriff somehow knew that but didn't go after him, and that's why the sheriff retired. Because he felt he couldn't do the job anymore...and he feels (dreams he let his dad down). Or you could say he knew the bad guy was behind the door...although that would be taking quite a risk, to walk by him and trust the guy would run, not shoot. OK, let us know who's right, who's wrong, or what totally different ideas you have. Thanks!
PS Also my SO for some reason thought the motel the sheriff went back to in the last scene was not the El Paso motel but the earlier one, but I think that makes NO sense! :)