'Murdered' in the Bible

"You know what Joab son of Zeruiah did to me -- how he murdered two commanders of the Israelite armies, Abner son of Ner and Amasa son of Jether. During peacetime he struck them down like he would in battle; when he shed their blood as if in battle, he stained his own belt and the sandals on his feet.

May the Lord punish him for the blood he shed; behind my father David's back he struck down and murdered with the sword two men who were more innocent and morally upright than he -- Abner son of Ner, commander of Israel's army, and Amasa son of Jether, commander of Judah's army.