The chairman of the Senate Homeland Security Committee says he plans to begin a congressional investigation of the shootings at Fort Hood.
An Army major, Nidal Malik Hasan (nih-DAHL' mah-LEEK' hah-SAHN'), is suspected of killing 13 people and wounding 29 others at the Army post in Texas.
Sen. Joe Lieberman says he wants to determine whether the shootings constitute a terrorist attack. He says he also wants to find out whether the Army missed warning signs that Hasan was becoming extreme in his Islamist views.
The Connecticut independent says if Hasan was showing signs of becoming an Islamist radical, the Army should have shown "zero tolerance" and discharged him.
Lieberman appeared on "Fox News Sunday."