Former Army psychiatrist Maj. Nidal Hasan is charged with opening fire in a troop processing center at Fort Hood, Texas, and killing 13 people and wounding more than 30 others in 2009.
Hasan is representing himself in the death penalty case.
NPR's Wade Goodwyn tells Morning Edition co-host Renee Montagne that means Hasan will be questioning witnesses he is accused of shooting.
Hassan is paralyzed from the waist down after being shot by a military police officer during the rampage.
On All Things Considered last night, NPR's Daniel Zwerdling told co-host Melissa Block that Hasan will be brought into the courtroom in a wheelchair.
Hasan is a Muslim and has maintained he was justified in his actions because he was protecting the Taliban from U.S. aggression.
He has tried to plead guilty. The military tribunal, however, would not allow him to do so, because under military statute, if you could be executed for a crime, you can't plead guilty.
The trial is expected to last months.