 It is revealed that after the death of Lance Sweets, Zack harmed himself, leaving a large scar on his forehead and occasional blackouts from minor brain damage.After being allowed to consult the evidence files of the Puppeteer case with Brennan, he concludes that, while blacked out, he committed the crimes, and wishes to return to the mental institution that is his home.In a surprise turn of events, the team at the Jeffersonian find out that it is Zack's doctor from the institution, Dr. Mihir Roshan, that has been committing the murders and arranging the skeleton marionettes.