HOUSTON -- A man was applying for a job with the federal government when his answers during a pre-employment polygraph test led to even more questions. As authorities dug deeper into Joseph Montross' life, they said they discovered evidence that he had been sexually assaulting children.

Prosecutors said Montross had applied for a job with the Department of Homeland Security, seeking a job as a border patrol agent. His application was going along fine until he failed the lie-detector test.

That test failure led to an investigation that uncovered thousands of photos of child pornography on his computer, said prosecutors. Montross is accused of taking photos of kids using a hidden camera that was in his shower.

The investigation was conducted by the Internet Crimes Against Children Task Force, which is actually headed by the Pasadena ISD police force. The task force includes officers from almost every area law enforcement agency.

Some of the children photographed were related to Montross, said police.

Harris County prosecutor Eric Devlin said young relatives of Montross were taken to the Children's Assessment Center where they allegedly told investigators they had been abused.

Montross was charged with aggravated sexual assault of a child, indecency with a child, promoting child pornography and two counts of possession of child pornography.