Is DHS overstepping its authority?

After a recent lapse in security allowed Umar Farouk Abdulmutallab to carry an explosive device aboard a U.S. bound aircraft, the Transportation Security Administration created and distributed a security directive which was leaked to 2 bloggers.  Stephen Frischling and Chris Elliot, both travel bloggers received copies of the confidential TSA directive.  Two days later, agents of the TSA appeared at the homes of both men with subpoenas demanding to know their sources.  How far does the authority of DHS and the TSA extend?  Is the TSA overstepping their authority by sending agents to serve subpoenas and collect evidence and testimony?  Perhaps I’m confused, but this seems like the specific territory of the FBI.

When U.S. President George W. Bush created the Department of Homeland Security on Nov. 25, 2002, the goal was to improve communication and response time by bringing a host of government entities under one umbrella.  DHS integrates elements of government such as the Coast Guard and Border Patrol, but does not include agencies such as the FBI, CIA or NSA.  (though DHS does coordinate communication between these agencies in matters relating to terrorist threats)

The TSA is understandably concerned about leaks from within their ranks, but I think they need to look at the larger situation.  A bad decision was made in releasing the directive at all.  It’s obvious to even the casual reader that very little thought went into it’s creation.  The directive was a knee-jerk reaction to a situation caused by a lapse in intelligence.  In typical TSA fashion, the directive did very little to address the root of the problem and focused primarily on instilling fear and confusion in the minds of travelers.  DHS and the TSA would be better off putting their collective effort into fixing the problem that led to the intelligence failure.