ABC News

ABC News' Reena Ninan reports:

Police say a Maryland man trying to film two female roommates with hidden cameras instead filmed himself and unwittingly helped authorities catch him in the alleged act of peeping.

Michael Stephen McKenny, 42, was arrested Thursday after Maryland police released footage of the alleged Peeping Tom setting up his cameras, which the women found.

"What we found is that the camera had been set up in June and operated through a motion detector," said Sherry Llewellyn, a spokeswoman for the Howard County Police Department.

In court documents, police say that for more than four months McKenny captured images of the unnamed women in their bathrooms and bedrooms, in all stages of undress, even using the toilet. Authorities say McKenny was brazen in his actions, entering the Ellicott City condo multiple times during the day to reposition his leering lenses. He even appears at one point to wipe away his own footprints.

"He knew these young women and he stole their keys, copied them and returned them before they had an opportunity to notice," Llewellyn said. "This isn't the first time this has happened here. People are able to do these kinds of things very surreptitiously."

Indeed, this is just the latest of similar incidents across the country.

Roommates in Tampa, Fla., demanded answers after they found an elaborate camera system in their apartment last year.

"I just want to know what he had planned with our videos, I want to know the whole story because now I don't know," alleged peeping victim Ralitsa Dzhambazova said.

Prosecutors in Tampa later dropped the case, saying the cameras were never turned on.

In Ohio, police say a man made his intentions clear when he allegedly put his cellphone under a dressing room door. Nancy Yingling, the alleged victim, was none too pleased.

"I pushed him and punched him in the face so he went down," Yingling said.

That man was charged with voyeurism, but has not been convicted of a crime.

As for McKenny, he has not yet entered a plea but could face up to 40 years in prison.