BLITZER: We're following new developments about the shooting that killed a U.S. border agent in Arizona. Lisa Sylvester is back. She's monitoring that, some of the other top stories in THE SITUATION ROOM right now. What are we learning?</s>LISA SYLVESTER, CNN CORRESPONDENT: Hi there, Wolf. Well, CNN has learned that the FBI is looking into the possibility that the shooting was a result of friendly fire. One agent died and another was injured Tuesday when they came under fire after responding to a border sensor. A law enforcement official says investigators are waiting for the results of ballistic tests on shell casings, which may have been fired by border patrol agents. And a well-known Cuban blogger has been arrested and two others reportedly detained in the eastern city covering a trial of a Spanish politician charged in the death of a prominent dissident. A pro- government blogger accuses of putting on a media trial. The federal government posted more than a $1 trillion deficit in the last fiscal year according to new estimates by the Congressional Budget Office. That makes the fourth straight year of trillion dollar shortfalls. The total national debt now tops $16 trillion. And the "Curiosity" rover is preparing to scoop up soil samples on the red planet. Beginning tomorrow, the "Curiosity" will use the robotic scoop to dig into the ground on Mars. Scientists will use the sandy soil to scrub the hardware clean. And that should clear the way for future testing of sediment to see if life possibly once existed on Mars. I know a lot of people are fascinated by this. So we're going to see what comes of those soil samples -- Wolf.</s>BLITZER: I'm looking forward to it.</s>SYLVESTER: Yes, me too.</s>BLITZER: Coming up, some late-night comedy it's getting political.</s>UNIDENTIFIED MALE: President Obama said the one thing about being president is learning to say no. Yes, especially when someone asks, do you feel ready for this debate?
Agent Killed In Friendly Fire?; Dissident Cuban Blogger Arrested; Deficit Tops $1 Trillion For Fourth Year; "Curiosity" To Scoop Up Martian Soil