FORT HOOD, Texas (AP) — The Army psychiatrist convicted of the 2009 Fort Hood rampage is starting the sentencing phase of his trial facing a possible rare death sentence in the U.S. military justice system.

Maj. Nidal Hasan on Monday returns to the courtroom on the Texas Army post where jurors last week convicted him of the deadliest mass shooting ever on a U.S. military installation.

The 42-year-old Hasan will spend the rest of his life in prison at a minimum. But prosecutors want the death penalty and will make their case by putting about 20 people on the witness stand.

Many of those will be relatives of the 13 people killed in the attack. Hasan hasn't indicated whether he will address jurors before sentencing.

Jurors must be unanimous to sentence him to death.

MICHAEL GRACZYK, Associated Press
NOMAAN MERCHANT, Associated Press

Copyright 2013 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.