MINNEAPOLIS, Minnesota -- Parents and others are demanding answers in Minnesota after authorities say a registered sex offender snuck onto a bus that took kindergartners on a field trip.
Maggie Zimmerman says she replays what happened on February 28th over and over in her mind, WCCO-TV reports.
"As a chaperone, I felt guilty. Like, why didn't I walk up and down the bus as soon as I got on it," Zimmerman said.
She was a chaperone for the daughter's kindergarten class field trip to the walker art center.
After a day of fun, it was time to get on the bus and return to Saint Paul.
"Pulled up, we loaded all the kids on, did a count, made sure we had everybody and started down the road," she said.
Zimmerman says there were two chaperones, a teacher and teacher's aide on board. She says a chaperone separated the 26 students on board from the rows of empty seats in the back of the bus.
"When we got onto (Interstate) 94, our teacher said she saw a man at the back of the bus," she said.
At first, no one noticed the stranger on board.
"When we looked back again he popped his head up and popped back down," Zimmerman said.
The bus driver told the man to sit up front while she called dispatch.
"During the drive back he asked to be let off a couple of times, would she pull over and let him off and she wouldn't," Zimmerman said.
When the bus returned to Chelsea Heights Elementary, 61-year-old Michael Friedrichs, a registered sex offender, was arrested.
His crimes include engaging in sexual activity with two 15-year-old boys, as well as exposing himself to elementary school children on a Minneapolis school bus in 2011.
School officials told parents how they believe he got on the bus.
"The school told us the footage from the camera shows him prying open the doors at some previous location prior to getting to the Walker when the bus driver was off the bus," Zimmerman said.
Friedrichs was released from custody and now Minneapolis police have launched an investigation into his registration violation and his conduct on the bus.
Friedrichs was released from prison in April 2018.
Authorities say he currently lives in downtown Minneapolis homeless shelters.
Registered sex offender accused of sneaking onto school bus full of kindergarteners