US Army soldiers comfort each other at the Fallen Soldier Memorial at Fort Hood on November 10, 2009 during a ceremony honoring the 13 soldiers and civilians killed in a shooting rampage at the army base on November 5. US Army Major Nidal Malik Hasan, 39, a psychiatrist and specialist in combat stress, who allegedly killed 13 people and wounded 42 in a shooting rampage, is believed to have acted alone by investigators and no motive has been established. Getty Images logo Getty Images 27 months ago

US Army soldiers comfort each other at the Fallen Soldier Memorial at Fort Hood on November 10, 2009 during a ceremony honoring the 13 soldiers and civilians killed in a shooting rampage at the army base on November 5. US Army Major Nidal Malik Hasan, 39, a psychiatrist and specialist in combat stress, who allegedly killed 13 people and wounded 42 in a shooting rampage, is believed to have acted alone by investigators and no motive has been established.