FORT BRAGG, N.C. -- The chief witness against a paratrooper accused of murder in last year's invasion of Panama acknowledged that he shot an unarmed Panamanian in the back during the operation.

1st Lt. Brandon Thomas, the first witness at the court-martial of Master Sgt. Roberto Bryan, said under cross-examination that he was searching his Panamanian prisoner when the prisoner ran away. Thomas said he did not know the prisoner was unarmed until after he had shot him.

Bryan, an 82nd Airborne Division paratrooper with a distinguished 19-year record, is accused of shooting another Panamanian without provocation on Dec. 23, three days after the United States invaded Panama to oust dictator Manuel Antonio Noriega.

He does not deny killing the man, but maintains the shooting was justified.

If convicted of unpremeditated murder, the military equivalent of second-degree murder, Bryan, 42, could be sentenced to life in prison.

The shooting by Bryan occurred after a Panamanian tossed a grenade that wounded 10 soldiers of the 82nd Airborne at a roadblock, authorities said.

Thomas testified that he grabbed Bryan's M-16 rifle and said, ". . . What the hell are you doing? He was almost dead anyway. You didn't have to empty a magazine into him."

The lieutenant testified that Bryan stepped back with a startled look on his face and said, " 'He injured my people.' "