BARTOW, Fla. – A former press aide for the federal Homeland Security Department pleaded no contest Tuesday to charges that he had sexually explicit online conversations with someone he thought was a 14-year-old girl.

Brian J. Doyle, 56, who resigned from the department shortly after his April 4 arrest, faces up to five years in prison under the plea agreement. The deal calls for 10 years of probation and requires him to register as a sex offender for the rest of his life, prosecutors said. His sentencing hearing is set for Nov. 17.

“I just want to say one thing. I am very, very sorry,”Doyle said outside the Polk County courthouse.

Doyle, of Silver Spring, Md., could have been sentenced to up to 115 years in prison if convicted of the 23 felony charges, including 16 counts of sending pornographic movie clips to a minor.

Prosecutors said Doyle wrote graphic descriptions of sexual acts in online chats and tried to set up a meeting with a 14-year-old named”Ashlynne,”who was actually a county sheriff’s detective.

According to court records, Doyle bragged about his government connections, showed off his department ID and may have used his official computer in the communications.

Doyle’s attorney, Barry Helfand, said his client suffers from depression.

While the case raised questions about homeland security hiring, Secretary Michael Chertoff said it was an individual’s”misstep,”not a security breach.

Under Florida law, a defendant making a no-contest plea settles the charge without admitting guilt.