Friends say Skinner had stopped taking the drug because it had made him feel like the "walking dead".
A friend is said to have found a pill on a table in Skinner's room recently and identified it as Quetapel.
Yesterday, it was revealed that Skinner had applied for a bridging course at the University of Auckland and wanted to study law.
James Stirling told the Herald Skinner's attempted home invasion was "such a bizarre thing to have happened".
He said he knew about Skinner's US trip but not about the girl.
"It was slightly short notice but not too out of the ordinary. He talked about spending some time with friends in Portland, Oregon and yeah just hiking, that kind of thing," he said.
"If he had mentioned it to anyone we would've told him how absurd it was and it would've ended there."
Stirling said he'd known Skinner since he was 12 years old.
"He's never come off as creepy or anything like that."
He said Skinner, an avid video gamer, had until now led a pretty normal life.
"He had some friends he enjoyed spending time with. Socially he was more or less normal."
Stirling said he was supposed to be starting his bridging course at the University of Auckland soon.
A spokesperson at the University of Auckland confirmed Skinner had applied for the course, which was due to start in two weeks.