NBA Referee Ron Garretson's DUI Arrest on Body Cam Video

Ron Garretson was a bloody mess after crashing his car and slightly before he got arrested for DUI -- but that doesn't mean he forgot his manners with cops.

The veteran NBA referee had blood all over his hands Wednesday as a Lake Havasu City police officer responded to the scene of the car wreck. In body cam footage, you can see Garretson was on his own two feet after hitting a tree ... but he seemed far from okay.

As the officer tries asking him questions to figure out what had happened, Garretson extends his hand for a shake -- but gets turned down ... twice. Bloody hands? No thanks, dude.

Garretson tries explaining what happened, but at times comes off as somewhat scatterbrained in piecing his story together. He says "a chick" hit him as he was circling around a road divider. Check out the windshield too -- it's completely cracked ... Garretson appears to have smashed his head against the glass.

As the 911 caller noted to dispatch, Garretson came off as fairly coherent right after the accident. But, as cops investigated further and had him perform field sobriety tests ... they suspected he'd been drinking and driving. LHCPD says he admitted to having a shot and a beer beforehand.