The U.S. attorney's office said Friday it did not find evidence that Sgt. 1st Class Trey Scott Atwater knew he was carrying C4 aboard his carry-on bag Dec. 31 at the Midland airport.
The 30-year-old was charged with trying to bring explosives onto an airplane.
Atwater has told the FBI he's a demolitions expert and had returned from his third tour in Afghanistan in April. He said his Army special forces team always carried C4 and that he didn't know it was in his bag when he returned from his most recent deployment.
A message left with Atwater's attorney was not immediately returned.