However, Mr. Colby was a child molester, and during his first sojourn in January 1988, filling in for Mr. Raditch (who had just had an appendectomy), Colby began to improperly touch and look at Lucy Fernandez; Wheels was coincidentally up at his locker (adjacent to the door of Raditch's English classroom) and saw Colby touching Lucy.
Later, in the spring, Mr. Colby returned to fill in for Ms. Avery (for an unspecified illness), and this time, he targeted Susie Rivera, by chumming up close to her while she worked on photos for the school yearbook. Lucy vaguely warned Susie, but Lucy felt it was her own fault back in the wintertime.
Eventually, however, Lucy realizes something must be done, and she and Wheels convince Susie to go along with them to report Mr. Colby to Mr. Lawrence. The rest is then solved.
- He was the first authority figure to harass a student. The second is Asher.
- Mr. Colby is the first character to sexually harass someone. The second is Asher Shostak and the third is Neil Martin.
- Mr. Colby is one of the six teachers to be crushed on by a student. The other five were Ms. Hatzilakos, Mr. Oleander, Mr. Simpson, Ms. Oh, and Grant Yates.
- Mr. Colby, along with twelve other characters has sexually assaulted someone:
- He sexually harassed both Lucy and Susie.
- A random stranger almost molested Wheels in his car while Wheels was hitchhiking.
- Liz's mother's ex boyfriend molested her when she was a child.
- Jordan held Emma captive in a room and almost raped her
- Dean raped Paige at a party
- An unidentified serial rapist spiked teenage girls' drinks at a party and raped Darcy.
- Mr. Valieri molested Jane as a child.
- Coach Carson tried to have K.C. have sex with a hooker against his will as well as had him watching porn.
- Lovequeen16 almost molested Connor in her car.
- Anson almost raped Bianca
- Vince forced Bianca into sex on numerous occasions
- Asher sexually harassed Clare
- Neil sexually harassed Maya and has taken advantage of and gang raped Zoë alongside Luke
- Luke has taken advantage of and gang raped Zoë alongside Neil.
- Grant Yates statutorily raped Tristan and attempted to grope Winston.