Major Nidal Malik Hasan, the 39-year-old military psychiatrist who allegedly went on a shooting rampage a week ago at Fort Hood in Texas, was tonight charged with 13 counts of premeditated murder, with the US Army's prosecutors expected to seek the death penalty.

At a press conference at the Texas military base, Chris Grey, a spokesman for the Amy's criminal investigation division, outlined the charges against Major Hasan and said that others might follow.

The psychiatrist is expected to face a military court martial rather than a civilian trial. If convinced, he would join nine other soldiers on military Death Row at Fort Leavenworth, Kansas. The last US military execution was carried out in 1961.

Mr Grey also advised the media against speculating about how Major Hasan's alleged massacre was stopped.

Credit was initially given to a female civilian police officer, Kimberly Munley, but it has since been suggested that it was in fact her partner, Mark Todd, who opened fire on the suspect. "Both [officers] engaged the suspect," said Mr Grey. "I would caution anyone from speculating about who did what until the investigation is complete." He added that he would "not be releasing any details [about the case] that might jeopardise any futher proceedings — our investigation remains ongoing".

However, Mr Grey confirmed that "we still believe there was only one gunman at the scene" adding that Major Hasan was "not at the readiness centre [where the shooting to place] for any scheduled appointments".

Mr Grey said that autopsies had now been completed on all the shooting victims, and that Major Hasan remains in hospital.

In interviews on Wednesday with the US media, Major Hasan's lawyer, retired Army Colonel John Galligan, said that his client was heavily sedated.

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