Colleen Griebel

 was Bobby Zierath's teacher.

Colleen became concerned about Bobby's story of imaginary friends. She was also concerned that this made him the butt of other children's teasing. However, she only intervened when Bobby got into fights with the other children.

Colleen was present at the meeting between Bobby's father, Victor Zierath, and Brent Uden of child protective services. (PROSE: The Schoolboy's Story)