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The Department of Homeland Security, which oversees the Transportation Security Administration, sent federal agents to the homes of two journalists and served them with subpoenas on Tuesday night to try to identify the source of a leak about aviation security changes imposed after the failed attempt on Christmas Day to blow up Northwest Flight 253.

In separate visits, the DHS employees told Chris Elliott and Steve Frischling that their computers and all e-mail correspondence related to the leak of the security directive were being subpoenaed as part of an investigation into who leaked the document to them, which both journalists published on their Web sites.

The directive, issued within hours after 23-year-old Umar Farouk Abdulmutallab failed to detonate explosives that had been sewn into his underwear, restricted passenger movement and activities on all international flights. After being published by Elliott and Frischling, the restrictions were widely ridiculed by travel experts, bloggers, and news organizations, which deeply embarrassed the TSA and the homeland security agency, already under pressure for their missteps in the foiled attack.

The TSA backtracked almost immediately on the restrictions -- which had ordered airlines, among other things, not to permit passengers to go to the bathroom an hour before arrival on all international flights and to prevent them from holding pillows, blankets and personal possessions on their laps. A TSA spokesman said that the added security precautions were discretionary.

Elliott, the blogger who first published Security Directive SD-1544-09-06 and writes a travel column for The Washington Post, said he was surprised and somewhat intimidated by the TSA visit and being served with the subpoena. In his blog, Elliott wrote that he had "just put the kids in the bathtub when Special Agent Robert Flaherty knocked on my front door with a subpoena. He was very polite, and used "sir" a lot, and he said he just wanted a name: Who sent me the security directive?"

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Elliott said in an interview that he had declined to tell Flaherty the identity of his source or turn over his computer. He said he has referred further inquiries about his stance to Mark Holsher, an attorney, who did not return calls for comment. The TSA later gave Elliott two weeks to comply with its subpoena.

Frischling, who runs a travel Web site called "Flying with Fish" and published the directive minutes after Elliott, said in an interview today that he had given his computer to the two federal agents who came to his house on Tuesday night. Frischling said he complied with their request after they asserted that he was "not a journalist" and handed him a subpoena, telling him he had now been "served." They also said they would return the next morning to confiscate his computer and other communications equipment if he failed to cooperate.

Frischling said his computer was returned this morning with several corrupted sectors and that he was running software to repair it. He said he had given the agents his computer because the directive had been sent to him anonymously, that he had deleted the original e-mails, and that it had been sent to him by someone who had undoubtedly used a phony e-mail name and address.

Francis DiScala Jr., Fischling's attorney, criticized the DHS for using "heavy-handed tactics" and "intimidating" his client. "Federal agents came and confiscated the tools of his trade at night in front of his three children," DiScala said. "When federal agents show up at your door with badges, their very presence is intimidating. The weight of the government is on you and just you. Steve was not motivated by generosity in giving up his personal computer, which he uses to earn a living."

Frischling said that the subpoena he received Tuesday, which was first reported by the Daily Kos, was almost identical to that posted by Elliott on his Web site. That subpoena, issued by the administrator of the TSA and the Department of Homeland Security, orders him to "produce and permit inspection and copying of the records" related to the inquiry to Special Agent Flaherty "no later than COB (close of business) December 31, 2009, in furtherance of an official investigation." The subpoenas order the recipients to produce "all documents, e-mails, and/or faxsimile transmissions in your control possession or control" regarding the "receipt of TSA Security Directive 1544-09, dated December 25, 2009."

The subpoena also warns that failure to comply makes the recipient "subject to fines" and "imprisonment for not more than one year," or "both."

Flaherty, who is based in a TSA office in Orlando, Florida, did not return e-mails asking him for comment on his investigation, or why he and other agents went to the journalists' homes at night.

Spokesmen for the Department of Homeland Security declined comment on the inquiry and subpoenas. The TSA, which never posted its regulations which are set to expire after Dec. 30, confirmed the existence of a leak investigation. Its statement asserted that security directives were "not for public disclosure" and that the TSA's Office of Inspections was "currently investigating how the recent SDs were acquired and published by parties who should not have been privy to this information."

Both the TSA and its parent Department of Homeland Security have been heavily criticized not only for the temporary security restrictions but for their handling of the terrorist incident more broadly. The transportation agency has been lambasted, for instance, for having allowed Abdulmutallab to board the Detroit-bound flight that originated in Nigeria with virtually no luggage and having bought a round-trip ticket in cash. DHS Secretary Janet Napolitano has also faced heat for having initially asserted in talk shows Sunday that the aviation security system worked well because the attack was foiled and other planes in the air were informed of the incident soon after the foiled attack took place.

Stung by the criticism, Napolitano reversed course on Monday, saying her remarks had been taken out of context, and that the incident had raised troubling security concerns. On Tuesday, three days after the incident, President Obama emerged from his vacation seclusion in Hawaii to deliver a broadside attack on the handling of the incident, saying it reflected a "systemic failure" that he considered "totally unacceptable." He has ordered a review of the incident, which he called a "catastrophe." A preliminary copy of that review is supposed to be delivered to him Thursday.

That the TSA would spend time and resources pursuing journalists about the origins of the leak of its security directive rather than focusing on finding how Abdulmutallab was able to board the plane despite intelligence indicating he was a potential security risk says much about the agency's priorities.

Elliott said he did not regret having published the directive, since he was a "consumer advocate trying to help the flying public." The TSA's security restrictions following the failed attack, he said, were "poorly thought through and didn't match up with what the TSA was telling the airlines." No one knew what was going on, he said "because the TSA did not respond" to his questions. He published it, he added, because the document did not state that it was secret or classified. "And that's what led to the knock on my door."

Lucy Dalglish, who heads the Reporters Committee for Freedom of the Press, a non-profit group which defends reporters and news organizations fighting for freedom of expression, said that the subpoenas "border on the ridiculous."

"Certainly TSA is enraged that it's order not to release this information was violated. Yet, there's nothing national security-related in the directive posted by Chris Elliott," she said.

She said it pertains more to what travelers already know: "Carry-on luggage is being searched and folks are being frisked at the gate."