Merabishvili told reporters Arutyunian opened fire on police to evade capture in the town of Vashlisdzhvari last night.
"According to preliminary information, as [police] were entering the house of the suspect, Vladimir Vladimirovich Arutyunian, he opened fire and killed one of our men, Zurab Kvlividze."
Arutyunian, who was injured in the shootout, was later captured.
Arutyunian is suspected of throwing a live grenade toward a podium where Bush and Saakashvili were speaking on 10 May. The grenade landed 30 meters from the podium but did not explode -- apparently because of a malfunction.