Probable cause, Officer!
Given what Accutane is prescribed for (severe acne) and some of its other side effects (if not carefully monitored, sometimes instead of relieving the symptoms it even causes increased inflamation), it's easier to believe these kids are depressed and have self-image problems to begin with - and if the treatment doesn't seem to be working, I can easily imagine that setting someone off.
"Beware of bugs in the above code; I have only proved it correct, not tried it."
-- Donald Knuth