Benson most likely had a background in either military, law enforcement or some other security based profession before joininf the Westworld QA Security Force.
Benson assisted Charlotte Hale in the retrival of Peter Abernathy during the Attack at Forlorn Hope. Benson and another member of QA entered the fort, stunned Abernathy and managed escort him out of the fort. They didn't seem to notice Bernard Lowe. While leaving, they were spotted by Dolores Abernathy and Teddy Flood, who chased them. Dolores managed to kill the two QA-members and injure Benson, but he managed drive away, with Charlotte Hale and Abernnathy.
Angela managed to capture Benson, and it's implyed that she tortured him to get information about Peter Abernathy. She brought the man to Dolores, where he confirmed that Peter was being held in the Mesa Hub. Due to his injuriy, Hale presumably threw him out, in order to not slow her or Peter Abernathy down.
Benson was interrigated by Dolores Abernathy about where in the Mesa Hub Peter Abernathy was held. Despite fellow human-employee Phil's pleas Benson couldn't answer, stating that Charlotte Hale. The reprogrammed Teddy Flood shoot him then in the head, stating that they didn't need him to find Peter.