Shooting potential messengers

Iraq Sought Missile Parts

Here’s another tidbit from the Kay report:

Kay said Iraq’s top nuclear scientist, Khalid Ibrahim Sa’id, had been killed during the war when his driver ignored a warning to move away from a Marine roadblock in Baghdad. Another Iraqi scientist frequently questioned by the U.S. team was fatally shot in the back of the head. A second scientist cooperating with the Americans was shot six times but survived.
Kay said that his team no longer interviews scientists in their homes or neighborhoods but has designated random places to meet, and that it has relocated some scientists and their families to other Middle Eastern countries for their safety.

I understand that ANYONE who cooperates with the US is a potential target for Saddam loyalists, but if there’s nothing incriminating to be told, why kill them? Just wondering.