A man who worked for a Homeland Security Department contractor has pleaded guilty to receiving thousands of photos and videos of child pornography.

Prosecutors say they consider Peter W. North, of Alexandria, to be one of the nation's most prolific distributors of child pornography.

North was arrested in August and pleaded guilty Wednesday in federal court. The computer specialist faces a minimum of five years in prison when he's sentenced in December.

According to an FBI affidavit, he was found with 80 gigabytes of child pornography on an external hard drive.