this may be largely a myth.
I believe that PCP is now relatively rare in the US and probably in much of the world. Its popularity in the late 70s was due to the easy availability of its precursors, which are now closely watched (particularly piperidine). Since ketamine has become rather common, and changing attitudes have made PCP less desired among its original user group, the demand for PCP is probably not large enough to call for its production on a large scale. I'm not saying that PCP doesn't exist, but it's probably a lot less common than it once was.
PCP, being an NMDA antagonist, can produce psychotic symptoms in certain users. In those with schizophrenia (including mild, latent schizophrenia), the NMDA antagonists can cause psychotic episodes with even a small dose, and *most* users will experience psychosis at a larger dose. This psychosis *seems* to involve strange behavior and particularly a lack of sense of consequence for one's actions.
As for violence, it's entirely possible. Without the usual conscience, someone could think it's better to resist arrest than to cooperate (which it almost never is). Adrenaline is doubtless a factor in the strength of resistance -- but so is the anaesthetic effect of PCP. When the nightsticks start falling, they don't hurt. The usual motivation to stop resisting because of the pain is eliminated, as is the usual physical reaction to pain. It's entirely possible that a PCP user might get shot 6 times and keeping approaching, because they probably don't know they've been shot.
But the stories you hear may well not actually describe PCP users. It's entirely likely that old stories of superhuman strength and extreme violence exhibited by PCP users has led to police officers thinking a suspect is on PCP if they seem to resist violently, even if they're really only on alcohol or meth or something entirely different.
In summary: PCP probably doesn't make people violent, but it may make already violent people prone to extreme violence in a fight because they can't feel pain.
