WASHINGTON (AP) - The fired chief of staff for Sen. Lamar Alexander made his first court appearance Thursday on charges of possession and distribution of child pornography.

Ryan Loskarn answered softly, "Yes, sir," when U.S. Magistrate Judge John M. Facciola asked Loskarn whether he understood that he was charged with serious offenses.

Prosecutor Mi Yung Park argued that Loskarn, 35, was a flight risk and danger to society and asked the judge to hold him until a preliminary hearing Monday, when Loskarn will enter his plea. Facciola agreed to the prosecution's request.

The defendant wore blue jeans and a gray pullover shirt, and sported glasses. He faces up to 10 years on the possession charge, with no minimum, and five to 25 years on the distribution charge.

According to a filing with the U.S. District Court on Thursday, police used a ram to enter Loskarn's home the day before, and noticed that he put something on the ledge outside a wind ow. It turned out to a portable hard drive with videos depicting child pornography, according to the filing.

The filing states that in 2010, the U.S. Postal Inspection Service and Toronto Police Service were investigating a movie production company, a majority of whose films feature young nude boys, and found that Loskarn had made several purchases from the company in 2010 and 2011.

Then in October of this year, the filing said, federal investigators identified Loskarn's residential IP address on a peer-to-peer network offering files "with names that are consistent with child pornography broadcasting as a download candidate."

Loskarn was a rising star who had spent the past decade working his way up to increasingly important posts in the House and then the Senate.

Alexander, R-Tenn., said in a news release Wednesday he was "stunned, surprised and disappointed" by the allegations against his newly departed staffer. Rep. Marsha Blackburn, another Tenness ee Republican for whom Loskarn had worked as communications director, said she was "shocked, saddened and stunned."

Several messages left for Loskarn were not returned.

Video taken by WJLA-TV showed Loskarn being led Wednesday from his southeast D.C. home by U.S. Postal Inspector police, who put him in a black SUV. Loskarn appeared to be in handcuffs, although a coat was draped over his arms. A spokeswoman for the agency said she could not comment on the arrest.

Alexander initially placed Loskarn on unpaid leave Wednesday morning, but before the end of the day, he had replaced Loskarn with David Cleary, the senator's legislative director.

Alexander said in a statement that it will be up to the courts to judge Loskarn, but "under these circumstances, he cannot continue to fulfill his duties as chief of staff."

Alexander is a former Tennessee governor who also served education secretary under former President George H.W. Bush. He was first elected to the Senate in 2002. He said his office was fully cooperating with the investigation.

Loskarn had a wide range of media contacts both in Tennessee and Washington dating back to his days as a spokesman for Blackburn. He was a fierce advocate for his bosses.

Loskarn was well versed in Senate procedure and was considered a sharp prognosticator of how debates and standoffs would play out. He was known to share colorful anecdotes and keen observations about body language and mood in the Senate.

Other congressional staff and reporters were stunned by the news as word spread on Capitol Hill on Wednesday.

According to Loskarn's biography on his LinkedIn account and in previous communications for Alexander's office, Loskarn graduated from Tulane University in 2000 and went to work for Republican Rep. Wally Herger of California as a legal assistant.

He later was the communications director for Blackburn and eventually became staff director for the Senate Republican Conference.

Loskarn had served as Alexander's chief of staff for two years.