The FAA wants this dude!! 
http://www.cnn.com/video/#/video/us/2010/03/17/dnt.tx.low.flying.plane.kprc?hpt=T2
HAHA! what a jacka*s!
Not the brightest color in the crayon box. 
I’m betting it won’t be hard to find, not a huge number of those DA aircraft around. If it was a Cherokee or other common aircraft, might be a little harder.
I assume you’re talking about the people with their Jeeps parked all over the beach, disrupting the mating grounds of the endangered red and blue long horn sea turtle.
With dozens if not hundreds of people on the beach and a good number of them carrying cameras or cell phones with still image/video capabilities, it won’t be long before the FAA will have something with a clear shot of the tail number.
Back in the day, we used to go 4wheeling on the beach, great times. I can tell you that that dude would have been fixing dents from the beer bottles bouncing off that thing.
When I was but a wee lad I rode my bicycle to the local airport to pump gas, answer the unicom etc. They even paid me once in a while.
One thing I learned is that California State Parks have a 1000 ft. minimum altitude’ except for takeoff and landing. You won’t find that rule in the FAR’s. The police would not even investigate without an N# AND it had to be seen with the naked eye, no binoculars or blown up pictures.