Published: Oct 12, 2010 11:36 AM EDT
Updated: Oct 12, 2010 8:36 AM EDT

FORT HOOD, Texas (AP) - Witnesses to a gunman's rampage at Fort Hood will begin describing the attack for a military officer.

The testimony Tuesday will provide new details about the scene that unfolded nearly a year ago in a building where soldiers were making final preparations to deploy.

The Article 32 hearing involving Maj. Nidal Hasan will determine whether there is enough evidence to put the Army psychiatrist on trial. The hearing is expected to last at least three weeks.

The 40-year-old Hasan is charged with 13 counts of premeditated murder and 32 counts of attempted premeditated murder in the Nov. 5 attack. It was the worst-ever mass shooting at an American military base.

When the proceeding begins, Hasan will be sitting just a few feet from the witnesses.