Nothing is known about this man before the outbreak began, except that he worked for the Border Patrol agency.
While Colton was in the Construction Site, standing guard over the entrance to The Tunnel, this man was in the tunnel itself, presumably clearing it of Infected. When Sierra tripped the booby trap, this man came running, but believed Colton when he lied and said he didn't know who set off the wire. He leaves Colton to presumably search for Sierra.
Part Fourteen Edit
This guard is searching the tunnel for Sierra when a mining cart roles up behind him. He is joined by a second border patrol guard and he rips the cover off the cart only to have an Infected shoved into him by Sierra. The last we see of him is struggling on the ground with the infected.