The U.S. Army Psychologist who murdered 13 people at Fort Hood was sentenced to death on Wednesday by a panel of 13 senior military officers.

Nidal Malik Hasan was already found guilty of 13 counts of premeditated murder and 32 of attempted premeditated murder in the November 2009 massacre, which was the worst mass murder at a military base in the nation's history.

Hasan had exchanged e-mails with al-Qaeda in which he discussed the idea of being a martyr for attacking fellow soldiers. Hasan is an American-born Muslim, and he said he believed the killings were justified because he felt he was doing his duty to fight an "illegal war" in Afghanistan. Hasan said he picked November 5 because it was right around the time his unit was preparing to go to Afghanistan

He released documents to The New York Times, which included a mental health evaluation and other statements.

"I don't think what I did was wrong because it was for the greater cause of helping my Muslim brothers," he said according to pages he provided.

Prosecutors in the case were adamant about pushing for the death penalty, which is apparently rare in military cases. Lead prosecutor Col. Mike Mulligan elaborated on whether Hasan will die as a martyr or not.

"You cannot offer what you don't own; you cannot give away what is not yours," he said. "He can never be a martyr because he has nothing to give.....Do not be misled; do not be confused; do not be fooled. He is not giving his life. We are taking his life."