Liam Payne's Death, Cops Say Behavior Looks Like Effects of Hallucinogenic

7:40 PM PT -- Although police say Liam's behavior sounds consistent with that of "cristal" users, they still don't know if that drug was present in the room. We're told they're still waiting for test results on the narcotics and medications they recovered. Liam Payne was potentially under the influence of a potent drug, known to cause psychotic attacks and hallucinations, when he died ... according to police in…