Ft Hood is the topic of the day on Capitol Hill and across the Potomac at the Pentagon as the federal government begins fallout investigations of the massacre, hoping to answer a simple question:  How did this happen?

On the Hill, Sen. Jospeh Lieberman I.-Conn., chairs the first hearing on the issue, pushing ahead of a White House request to let them handle the investigation. 

At the Pentagon, Secretary of Defense Robert M. Gates and Chairman of the Joint Chiefs Adm. Mike Mullen will make their first appearance in the press briefing room since September 3.  The Associate Press has reported Gates will announce the details of the Defense Department review. 

Reporters also expect Gates to give his first extended remarks and face open questioning from the press corps about the tragedy and the investigation. 

The secretary released a short statement after the shooting, an unusual move for his press handlers.  Gates then met with victims in Texas, but the visits were closed to press.  Last week, he spoke with reporters traveling with him aboard his plane on the way to Oshkosh, Wisc., for a defense factory tour.  But Gates largely used that time to scold leaks about the investigation and the Afghanistan strategy review. 

On Wednesday, Gates quietly flew to Tennesee for the funeral of Spc. Frederick Greene, on the request of Greene's father. Pentagon reporters found out after the fact.  The secretary, who often gets emotional when talking about the dead and wounded young American men and women under his watch, has made several unannounced and never-publicized visits to Arlington funerals, and yesterday Gates took no press and no official photographer to Tennessee.

The secretary has faced the families.  This afternoon, back in Washington, Gates faces the lights.