ANKENY, Iowa (AP) — Authorities say a man disguised a video camera as an alarm clock so he could record a woman and her 11- and 12-year-old children when they used a bathroom in their Polk County home.

Court records say 53-year-old Brian Hoffman, of Lidderdale, pleaded not guilty Thursday to charges of invasion of privacy, unlawful interception of communication and two counts of sexual exploitation of a minor.

The woman described Hoffman as a friend after she called police to report her discovery of the camera. Police say the clock was placed to face the bathroom and the memory card was accessible through a wireless internet connection. Police say the card had several images of the woman and the children naked.

Hoffman told investigators he didn't know the clock contained a video device.