Beta was one of the security guards at the Guest House.
When S.H.I.E.L.D. agents Phil Coulson, John Garrett, Grant Ward and Leo Fitz approached the entrance of the bunker, Alpha and Beta were suspicious of them, because there was not a scheduled visit for the following weeks. So they tried following the protocol of these situations, asking a password to the approaching agents.
The agents hacked their way inside the bunker, and both guards acknowledged how good they were. When they reached the inside doors, the guards and the agents began a gunfight.
Beta was killed by Agent Garrett in the gunfight. Garrett went over his person after he was done. Upon finding and reading his ID, Garrett told him, "No hard feelings, Bob".
When Raina was given a handful of vials all labelled GH by John Garrett at the Barbershop Headquarters, she asked him from where he got them and if she could see the facility. He told her that a "couple of security chuckleheads hit the kill switch". 
- Alpha † - Colleague