The deputy press secretary for the US Department of Homeland Security was arrested Tuesday for using the Internet to seduce what he thought was a teenage girl, authorities said.

This undated image made available April 4, 2006 by the Polk County, Fla. Sherriff's office shows US Department of Homeland Security deputy press secretary Brian Doyle. Doyle, 55, was arrested in Maryland for using the Internet to seduce what he thought was a teenage girl, authorities said.  [AP Photo]

Brian J. Doyle, 55, was arrested at his residence in Maryland on charges of use of a computer to seduce a child and transmission of harmful material to a minor. The charges were issued out of Polk County, Fla.

Doyle, of Silver Spring, Md., had a sexually explicit conversation with what he believed was a 14-year-old girl whose profile he saw on the Internet on March 14, the Polk County Sheriff's Office said in a statement.

The girl was an undercover Polk County Sheriff's Computer Crimes detective, the sheriff's office said.

Doyle sent the girl pornographic movie clips and had sexually explicit conversations via the Internet, the statement said.

During other online conversations, Doyle revealed his name, that he worked for the Homeland Security Department and offered his office and government issued cell phone numbers, the sheriff's office said.

Doyle also sent photos of himself to the girl, but authorities said they were not sexually explicit.

On several occasions, Doyle instructed her to perform a sexual act while thinking of him and described explicit activities he wanted to have with her, investigators said.

Doyle later had a telephone conversation with an undercover deputy posing as the teenager and encouraged her to purchase a web camera to send graphic images of herself to him, the sheriff's office said.

He was booked into Maryland's Montgomery County jail where he was waiting to be extradited to Florida, the sheriff's office said.

There was no immediate response to messages left on Doyle's government-issued cell phone and his e-mail, and he could not be reached by phone at the jail for comment.

Homeland Security press secretary Russ Knocke in Washington said he could not comment on the details of the investigation. "We take these allegations very seriously, and we will cooperate fully with the ongoing investigation," Knocke said.

Doyle, who is the fourth-ranking official in the department's public affairs office, was expected to be placed on administrative leave Wednesday morning.