A 53-year-old Minneapolis man was charged Thursday with committing a sex act on board a school bus while children were there last month.

Michael Charles Friedrichs was carrying a backpack and posing as a student when he got onto the bus at 42nd Street and Longfellow Avenue S. about 7 a.m. March 17, according to police spokesman Sgt. William Palmer.

When Friedrichs left the bus, the driver, who had been on the job for less than a month, became suspicious. When he checked the area where the man had been sitting, he found slashed seats and evidence of a solo sex act, so the driver called radio dispatch to report the incident, police said at the time.

The bus was on a regular route, headed for Seward Montessori School. The Minneapolis School District notified parents about the incident shortly after it happened.

Friedrichs, who was arrested Wednesday, is charged with criminal sexual conduct in the fifth degree, a gross misdemeanor, Palmer said.

STAFF REPORT