Chief Warrant Officer Larry Caulfield was a soldier stationed at the Denver Quarantine Zone. He was the tactical advisor of Captain Regan's unit, which included two other members, Private Eugene Ellis and Warrant Officer Sean Brendon.
Little is known about Caulfield except that he joined the military and was put in Captain Regan's unit in the 4th Infantry Division, presumably for some time given his high rank. He was stationed in the Denver Quarantine Zone before going on a rescue mission with his unit. During the captain's birthday party, he celebrated with the rest of the unit, posing in a picture with them, which was then gifted to Regan stating she was "the coolest Captain around". Caulfield appears to be Caucasian. 
The unit crash-landed in the Colorado Mountain Plaza while returning to the Zone. The crew survived the crash, but one soldier, Sean, was attacked and killed by their infected patient. Caulfield killed the infected, Regan commenting on how "brave" he was, but was consequentially bitten. Upon discovering the bite, Captain Regan (following protocol) ordered Ellis to subdue Larry. Larry pleaded for his life, stating he still had time but Regan executed him regardless. She would later come to regret the decision. Regan initially lied in her report, claiming Larry immediately revealed the bite and willingly let Regan shoot him, undeterred by his fate. She later changed her mind and wrote a second report remarking she "shot him like a dog"