The United States army has formally charged the military officer accused of carrying out last week's mass shooting at the Fort Hood military base in Texas. The officer, Major Nidal Malik Hasan, an army psychiatrist, has been under armed guard in a hospital since being wounded in the shooting. Mathew Prize reports from New York. There are still many questions surrounding the mass shooting at the America's largest military base, but one of them has now been answered. Major Nidal Hasan, an army psychiatrist who was due to be deployed to Afghanistan, has been charged with 13 counts of murder. That could rise if prosecutors decide also to charge him with the murder of an unborn child being carried by one of his victims. He will be prosecuted in a military court. If convicted, he could face the death penalty, although no one has actually been executed under the US military justice system for almost 50 years.