A suburban Philadelphia landlord placed hidden cameras throughout his apartments and secretly videotaped female tenants for years, investigators said Monday.

Thomas Daley, 45, of Phoenixville, is accused of wiretapping, invasion of privacy and criminal use of a communications device, among other charges stemming from the police search that yielded cameras behind mirrors and in cabinets and ceiling fans, police said.

Hidden cameras and audio equipment were found in the bedrooms, bathrooms and living rooms of at least three apartments he owned in Norristown, police said. Altogether, 16 apartments have been searched or are in the process of being searched.

"He had such an elaborate system set up that when someone in the apartment would activate a light switch or a ceiling fan, he was able, via the Internet, to retrieve the video images or audio," Montgomery County District Attorney Risa Ferman said.

No cameras were found in apartments currently rented by men, she said. It was not immediately clear how many properties Daley owns.

Ferman would not disclose more details on the charges, including how many Daley faces or the number of apartments or tenants the charges involve. But police were getting numerous calls from former female tenants about the arrest and expect to find more victims.

"This is really the tip of the iceberg in a much larger case," Ferman said.

Daley, who was arrested Friday, told police he had been making the secret recordings for about 20 years, Ferman said. Police seized a cache of videotapes and DVDs.

"Some of the tapes were the old fashioned VHS tapes, and the more recent were digital — so it clearly spans several generations of technology," Ferman told The Associated Press.

Norristown police began to investigate after a tenant found a camera in her apartment. Wires to that camera led to a recording system in the basement.

Daley was being held on $1 million cash bail. His preliminary hearing was set for Sept. 29.

It was not immediately clear if he has a lawyer, and a message left at a phone number listed for Thomas Delay in Phoenixville was not returned.