Paul Walker Crash -- Scumbag Roof Thieves CAUGHT ON TAPE

Paul Walker's fans RECORDED FOOTAGE of the scumbags who stole pieces of the wrecked Porsche GT the actor died in ... and the video, obtained by TMZ, could help prosecutors put the bad guys behind bars.

The video -- shot by fans who were at the scene to pay tribute to the actor -- captured the moments when two men ran over to the Porsche, which was on a tow truck, and ripped off pieces of the roof.

The crooks then sprinted away from the car ... as the fans screamed at them to stop and honked their car horn to alert other people about the crime.

We broke the story ... cops were called and quickly arrested one of the suspects. The other man fled the state, but cops say they know who he is and expect the guy to turn himself in soon.