The female bystander, apparently not injured, confirmed the incident in an interview with KMPH.
The utility worker underwent surgery for non-life-threatening injuries, and the driver, who stood more than 6 feet tall and weighed at least 300 pounds, was arrested, the affiliate said.
McGillvary's story was featured on "The Colbert Report" and "Jimmy Kimmel Live."
Romankow acknowledged the Internet fame surrounding McGillvary, but said that means nothing when it comes to the accusations he is now facing.
"This man was well-known. That doesn't mean he did not or could not become involved in a crime," Romankow told reporters before McGillvary's arrest. "We believe he has murdered someone -- an attorney by the way who was in the county, was well respected, well regarded for well over 40 years."
"I believe that everyone is a little safer with this person off the streets," the prosecutor said after McGillvary's capture.