Captain A. Exeter was a character who appeared in Metroid Prime 2: Echoes for the GameCube. He, along with his troopers, were killed by an Ing attack. During the attack he attempted to send a distress call, though it didn't make it through the magnetic fields of the planet.
Samus Aran found him, along with the other dead Galactic Federation soldiers, before re-obtaining the missile launcher.
Not much is known about him, though he was the captain of GFMC Task Force Herakles, as confirmed through scans. His team was ordered to guard the GFS Tyr, which was ultimately destroyed. As you can see in the picture, his visor is cracked, revealing his left eye. When he dies, it is left open until Samus finds him and closes it out of respect.