|Out of universe information|
Mentioned in "Death Knell"
Riley was a Colonel in the United States Air Force and was the commander of the Alpha Site. When the base was attacked by Kull warriors, he ordered his second in command, Major Green, to evacuate to the tree line after the Stargate was hit by an Al'kesh. He stayed behind to make sure the self-destruct went off. (SG1: "Death Knell")