The "looks like he's on drugs" has an interesting connection to the "skittles and arizona tea". Those a street names for "ecstasy/dextromethorphan and marijuana laced with PCP". If the tox screen reveals PCP, that might explain a belligerent, aggressive attitude on the part of Martin. The admonishment from his brother about "taking a swing at the bus driver" on twitter suggests a tendency to get physically violent". We'll have to wait for more input. The real Trayvon Martin was a different person from the innocent looking 12-year old pictured by the press.
Ecstasy wouldn’t have had such an immediate effect, but PCP laced marijuana would. Rain might pose a problem with that line of thinking, he’d had to have smoked it somewhere. FL isn’t like CA and some other places, where an individual smoking marijuana in public wouldn’t attract attention, or at least central FL isn’t.
The effects might tend to coincide with known or reported behavior as well. Paranoia followed by aggression.