Evidence purporting to show how U.S. Army Major Nidal Hasan adopted a radical vision of Islam, including emails Hasan exchanged with American cleric Anwar al-Awlaki, was blocked by a military judge on Monday at Hasan's court-martial for shooting dead 13 fellow soldiers.
Judge Colonel Tara Osborn barred testimony about the correspondence between Hasan and Awlaki, the U.S.-born militant who was killed in a U.S. drone strike in Yemen in 2011, and with other militants.
Hasan, acting as his own defense attorney, has admitted he opened fire at Fort Hood, Texas, on Nov. 5, 2009, killing 13 and wounding 31, saying he switched sides in what he considered a U.S. war on Islam.
He could face the death penalty if all 13 officers on the jury find him guilty of premeditated murder.
The judge banned some evidence dating to 2005, declaring it "too remote and subject to multiple interpretations." She also blocked another exchange as a "waste of time and unfair prejudice."
More recent emails and internet searches, however, could be admitted as evidence, Osborn ruled.
That ruling cleared the way for FBI Special Agent Charles Cox, a computer forensics expert who examined Hasan's laptop after his arrest, who testified there had been 28 searches for the word "Taliban" in the months leading up to the shooting, as well as repeated searches for the word "ammo."
Early in 2009, Internet searches on the computer contained phrases such as, "killing innocent Koran" and "killing innocent women and children Koran."
More than 75 witnesses have testified in the court-martial over the past two weeks, many describing in horrific detail the bloodbath in and around a medical building at Fort Hood on Nov. 5, 2009.
Hasan, who was shot and paralyzed upon his arrest, attends court in a wheelchair. The judge has repeatedly reminded Hasan he would be better represented by a defense attorney, saying even a lawyer should not represent himself.
Hasan has said he will continue as his own counsel.
On Monday, Hasan questioned Staff Sergeant Juan Alvarado, who testified about witnessing the shooting, including an exchange of gunfire between Hasan and military officer Sergeant Kimberly Munley, who was wounded in the exchange.
"Were you watching the whole time while I and Sergeant Kimberly Munley were shooting at each other? You didn't look away at all?" Hasan asked.
"I was watching the whole time," Alvarado said.