Frank Bishop is an X Middle School Student.
Frank used to be a former partner of then-Safety Patrol Officer Vallejo, putting to use his deductive skills as a profiler. Unfortunately he was driven from the Safety Patrol in disgrace over a game scam case where he stopped the perpetrator in a fashion involving gazpacho, which the boy was allergic to, and the parents a lawsuit threatened against the school by the boy's parents who would only be appeased with his dismissal from the Patrol.
Years later when a crime cropped up involving 'The Shredder' –an anonymous criminal shredding student's pet projects– the Safety Patrol once again turned to Frank for his profiling skills. He deduced the Shredder was hitting students from the Drama Club in alphabetical order, and that his own sister, Francine was next on the list.
There were moments where it seemed Frank was himself the Shredder. However it turned out to actually be his sister, out for revenge on Vallejo before she was apprehended by Fillmore and Ingrid.
Frank may have returned back to the Patrol as Vallejo, running for his second term as Junior Commissioner, told him he was still in need of a good profiler.