WASHINGTON (CNN) -- A deputy press secretary for the U.S. Department of Homeland Security was arrested Tuesday at his Maryland home on charges he used his computer in an attempt to seduce a child and transmitted harmful materials to a minor, according to the Polk County, Florida, Sheriff's Office.

Brian J. Doyle, 55, is charged with seven counts of use of a computer to seduce a child and 16 counts of transmission of harmful material to a minor, according to a sheriff's office statement.

...in the first conversation, told the detective his position with DHS and "started immediately into pretty vulgar language. He explained in graphic detail the sexual acts he wanted to perform with this 14-year-old."

As the two continued chatting online, police said, Doyle gave her his home and office phone numbers, and the number to his government-issue cell phone. He also had explicit telephone conversations with a detective posing as the girl, authorities said.

In addition, he used the Internet to send "hard-core pornographic movie clips" to her, and also used an America Online instant-messaging service to have explicit online conversations with her.