Cox said more than 20 federal and state law enforcement partner agencies are involved in the investigation and search for the assassin.
The governor said the state has been working with its attorneys and getting everything ready to pursue the death penalty in this case.
During the same briefing, Utah Department of Public Safety Commissioner Beau Mason shared videos and photos collected by the investigation. The images show what appears to be a college-aged male who is suspected of having fired the shot that killed Kirk, 31, while he was speaking at Utah Valley University.
The suspect was dressed in a black t-shirt, black pants, a ball cap with a triangle in front, a pair of sunglasses, and a backpack. Investigators also think he was wearing Converse shoes. Trace evidence collected from the rooftop scene included shoe impressions, a forearm imprint, and a palm print, according to the FBI.
As a video was played, Mason explained how it showed the suspected gunman dropping down from the roof of the building where officials say the shot was fired. He then walks away, crosses a street, and heads toward a wooded area where investigators found a bolt-action rifle with the spent casing still in the chamber and four additional rounds in the magazine.