The deputy press secretary for the Department of Homeland Security was arrested last night on charges that he used the Internet to seduce an undercover Florida sheriff’s detective who he thought was a 14-year-old girl, the Polk County Sheriff’s Office said.

Brian J. Doyle, 55, was arrested at his Silver Spring home at 7:45 p.m. and charged with seven counts of using a computer to seduce a child and 16 counts of transmitting harmful materials to a minor, according to a sheriff’s office statement.

Agents with the department’s Inspector General’s Office, the U.S. Secret Service, the Montgomery County police and the Polk County Sheriff’s Office served a search warrant and seized his home computer and other materials, the statement said.

Doyle was online at the time awaiting what he thought was a nude image of a girl who had lymphoma, Polk County Sheriff Grady Judd said in an interview with Fox News’ “On the Record With Greta Van Susteren.” “We wanted to make sure he was using that computer and talking to detectives at the time of the arrest,” Judd said.

In his initial communication last month, Doyle told an undercover computer-crimes detective who he was and that he worked for the Department of Homeland Security, later disclosing numbers for his office phone and government-issued cellphone and using those lines, the sheriff’s office said.

“If he would provide that kind of information to include a photograph of himself with his identification tags, who else may he be talking to around the world who he thinks to be a 14-year-old girl?” Judd said on CNN’s “Anderson Cooper 360.”

Attempts to reach Doyle, who was booked into the Montgomery County jail on the Polk County charges, on his office and cellphone numbers and by his official e-mail were unsuccessful.

He was a TSA spokesman before becoming deputy press secretary last year to Homeland Security Secretary Michael Chertoff.

Chertoff press secretary Russ Knocke declined to comment on the case beyond releasing a written statement, saying, “We take these allegations very seriously and we will cooperate fully with this ongoing investigation.”

Judd said Doyle confessed and waived extradition to Polk County.

According to the sheriff’s office, Doyle initiated a sexually explicit conversation with the detective on March 12 in response to an Internet profile of a 14-year-old girl.

Doyle allegedly sent pornographic movie clips, non-pornographic photos of himself and instant messages from his AOL account, the police statement said. The sheriff’s office alleged that Doyle “on many occasions” instructed the undercover detective to perform a sexual act while thinking of him and described explicit acts he wished to perform.

Another Homeland Security official — Frank Figueroa, special agent in charge of U.S. Immigration and Customs Enforcement in Tampa — faces trial this week on charges of exposing himself to a teenage girl last year at a mall. Figueroa, who has been suspended, pleaded not guilty.