A US Army soldier leaves one of his military patches in front of a photo of his friend at the Fallen Soldier Memorial at Fort Hood on November 10, 2009 during a ceremony honoring the 13 people who were killed in a shooting rampage 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

A US Army soldier leaves one of his military patches in front of a photo of his friend at the Fallen Soldier Memorial at Fort Hood on November 10, 2009 during a ceremony honoring the 13 people who were killed in a shooting rampage 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.