CASCADE TOWNSHIP, Mich. (WZZM) - They've used dogs, decoys and surveillance, but somehow a serial flasher in Kent County is avoiding capture by the police.

"We've done a lot of patterning, used tracking dogs but have not been successful capturing the individual," says Undersheriff Jon Hess of the Kent County Sheriff's Dept.

They aren't positive, but investigators say the same individual may have exposed himself in Cascade Township dozens of times over the past several years.

"In the last six years I'm guessing we've had close to 30 occurrences of someone flashing," says Hess. "Over the last 12 months we've had at least 12 cases in that general vicinity."

Investigators have even set up decoys to trap the flasher.

When a woman working at a shopping plaza on Old 28th Street was flashed, deputies put an undercover officer in the "Essential Touch Therapeutic Massage" business next door.

"Somebody that would be in the office and hopefully get the fellow to expose himself to her," says business owner Ray Lanse. "They used it for about a week or so and were not successful.

The suspect is sometimes seen naked or nude below the waist outside an office or business.  Typically, he knocks on a victim's window and -- after she looks up and sees him -- he runs away.

"He's going for a surprise factor by knocking on a window," explains Undersheriff Hess. "Surprise and he's gone. It's obviously some sort of sickness or mental illness."

The flasher never tries to touch or even talk to anyone, but police fear his crimes could escalate.

"We don't want a sexual assault or anything worse," says Hess. "Anybody willing to take the chances to do this type of thing, there is the potential for them to do anything else. We just don't know."