You'd think that the police would have interviewed anyone with a comment by their name, or if they were on the "shit lists." But, we know Rocky Hoffscheider isn't interviewed in the 11k. So I'd venture to say no, they probably weren't all interviewed by the police.
Rocky was the notorious bully of Columbine, who graduated the year before Eric and Dylan would have. He was also reported to be on top of Eric's 'people from 1998 who should have died' list. (It wasn't worded that exact way, but I can't think of the title right now.)