Army Maj. Nidal Hasan admits he shot and killed 13 people at Ft. Hood on Nov. 5, 2009. But federal law prohibits anyone who faces the death penalty from entering a guilty plea.
South Texas College of Law Prof. Geoff Corn is also a retired Army Lt. Colonel. He says even though everyone knows Hasan went on a shooting spree, the prosecution still has the burden of proof.
"In our system of justice, the presumption of innocence applies to even the most obviously guilty defendant."
Hasan is charged with 13 counts of premeditated murder and 32 counts of attempted murder.
"And proving that, remember you have to prove this, is a very laborious task. The prosecution can't just assume that the defendant is going to admit guilt. They have to prepare the case as if he's going to plead not guilty and introduce the evidence that they have to introduce."
There are about 250 people on the prosecution's witness list.
Hasan will have the opportunity to cross-examine any of them who are called to the stand.
Corn predicts a conviction is inevitable and he says the sentencing hearing will be the most compelling part of the case.
"That's when the issue of death is going to be on the table. It only takes one "no" vote for him to not to get the death penalty."
The court martial was scheduled to begin 18 months ago, but was repeatedly delayed over legal issues including whether Hasan should be required to shave his beard.