A US army officer who killed 13 people in a rampage on a Texas military base was found guilty of premeditated murder and now faces a possible death sentence. The verdict against Major Nidal Hasan, 42, was handed down by a military jury after a court martial at Fort Hood, the site of his 2009 shooting spree. Hasan sat stoically as the forewoman, a colonel, read the verdict in the killings of 12 military service members and a civilian, as well as the attempted murder of dozens more. There were no outbursts of emotion from relatives of the victims, but some cried and wiped away tears as they left the courtroom. "So overwhelmed with joy and tears! ... God Bless the victims in their strength," former police sergeant Kimberly Munley, who was wounded in the shooting, wrote on Twitter. The trial had heard that Hasan, a Muslim, had been in contact with a leading al-Qaeda figure and had attacked his comrades out of opposition to the wars in Iraq and Afghanistan. Hasan, who was serving at the time as an army psychiatrist, chose to defend himself during the hearings and openly declared that he had carried out the killings. The trial will now move into a sentencing phase. His refusal to engage with the court - he called no witnesses and refused to make a closing statement - has fuelled suspicions that he is actively seeking the death penalty. Under US military law, a full trial must be held in a death- penalty case, even if the defendant wants to plead guilty. But Hasan chose to defend himself and contested virtually none of the evidence presented during the two-week court martial.