Ok, sure. Evidence of an act that's an element of the charge brought may certainly come in. IF he was charged with concealing evidence, how he concealed it would clearly be relevant evidence. But whether he broke into a classmate's apartment so she'd have him help her with a home surveillance system that he could later use to spy on her seems irrelevant to the charges brought (even in the unlikely event it could be proven the situation with the classmate actually happened.) And if there is evidence he routinely ran and/or drove around at night, that would seem to me to be evidence favorable to the defense, not the state. It would show his behavior wasn't unusual that particular night.
MOO