Back in 1965-66, a Milwaukee mass murderer named Michael Lee Herrington was roaming the streets. Herrington killed several people, including 11-year old Julia Beckwith and 19-year old Sheryl Thompson, the sister of Terry Thompson, with whom Dennis attended St. Rose of Lima Church and School. Years later, Terry and Dennis worked together at St. Charles Boys Home.
The facts of that case were a basis for O'Boyle's movie script, Valley Park, centering on the incidents surrounding Merrill Park, a real-life Milwaukee neighborhood where O'Boyle lived. He was chased by Herrington on at least two occassions, including a very frightening experience on Halloween night, 1965.
Dennis later became a bus driver and drove two mass murderers on his busses, including Jeffrey Dahmer and Roberth John Wirth. Every weeknight for almost two years, Dahmer would board O'Boyle's northbound Route 80 - 6th Street bus at 10:42 p.m. on the corner of S. 6th St. and W. Lincoln Ave. From there, O'Boyle would drive Dahmer north to Ambrosia Chocolate Co., located at the time on N. 6th St. near W. Highland Blvd.
The case involving Wirth (below) was historic as Wirth was the first murderer convicted with the help of DNA evidence in Wisconsin.
