Two days after serving two journalists with subpoenas demanding that they reveal a confidential source, a move that prompted widespread backlash among frequent fliers, the Transportation Security Administration has withdrawn the subpoenas and returned a damaged laptop to one of the writers.

A TSA spokesman claimed Thursday that its investigation into who leaked a December 25 security directive was nearing completion and the subpoenas were no longer necessary.

The directive, issued immediately after a failed Christmas Day terrorist attack on a Detroit-bound airliner, specified temporary heightened security measures which international airports were to use on U.S.-bound flights. The directive was to expire Wednesday but has been revised and extended through the weekend, according to Homeland Security officials.

Steven Frischling, a freelance photojournalist and travel writer who also blogs for KLM Royal Dutch Airlines, received a copy of the directive anonymously and published it on his personal blog, Flying with Fish, on Sunday. On Tuesday armed TSA agents arrived at his house with an administrative subpoena and threatened him into surrendering his laptop. The agents wanted to know who sent him the document.

Christopher Elliott, a syndicated travel columnist, also received the directive and published it at his personal blog. He too received visits Tuesday from armed TSA agents, but he declined to cooperate and informed them that he would challenge the subpoena. As a result, his laptop never left his possession and his livelihood was largely unharmed.

Frischling wasn’t so lucky. Though TSA returned his MacBook laptop Thursday, he reports that it was damaged and nearly unusable, according to Wired.

While many states shield journalists’ confidential sources, a federal shield bill which passed the House in March has been stalled in the Senate. Even so, the bill would exempt from protection information which the government claims would help prevent an act of terrorism or harm to national security.

It’s unlikely any information in this security directive would have any negative impact on national security if released, since affected airports and airlines also had to publish much the same information to assist travelers through the security procedures. It’s also clear that Homeland Security cares more about plugging leaks in its bureaucracy than plugging leaks in homeland security.

From my own experience with having federal agents at my door, let me say this: Remember that if law enforcement shows up at your door, you are in no way obligated to speak to them, and in no way obligated to hand over anything immediately if they hand you a subpoena. You can and should challenge (move to quash) such a subpoena in court, if you receive one. You only have to surrender anything immediately if they have a search warrant, and only if the thing is named on the search warrant. Other than that, say absolutely nothing until you can consult a lawyer. Be polite, of course, when you ask them for their business card and send them on their way.

Finally, from Frischling’s description, it would seem the computer’s hardware may have been modified. Reportedly the TSA has offered to pay for a new computer; if true, I suggest he take a check and buy it himself — from the Apple Store, not online.