Keller (Fallout: New Vegas)

Keller is an NCR Ranger working as an undercover agent investigating a chem ring in Westside in 2281.

Background
This undercover agent of the NCR police spearheads an investigation with Lt. Boyd into chems trafficking in the outer Vegas area. Keller, an NCR Ranger, for months, has been operating from the pawn shop in Westside, gathering evidence to break up the drug ring. He recently arrested a chem dealer named Price for supplying chem ingredients to the local gangs, such as the Fiends and Scorpions.

With the dealer behind bars and awaiting questioning, Keller meanwhile poses as an associate of Price, handling his deliveries while he is away, covering up his absence as a recent business opportunity that Price went to check out. In turn, the agent intercepts incoming packages for Price to be used as evidence in his trial and to expose more of his associates. One of the people that Price made deals with to transport chem ingredients, the Camp McCarran quartermaster Daniel Contreras, is held under suspicion by Keller for his involvement in trafficking.

Contreras soon sends one of his associates, the Courier, to deliver a package of medical supplies to Price, unaware that his contact has already been apprehended and locked up.

Quests
Dealing with Contreras: The Courier is sent to Miguel's Pawn Shop to find Price, Contreras' contact, but instead Keller is there. Talk to him and report back to Contreras. He'll ask the Courier to kill Keller, but they can convince Contreras to work with him, Barter check of 70 or Speech check of 80. Whichever option is chosen, return to Keller and either kill him or convince him to work with Contreras.

Appearances
Keller appears only in Fallout: New Vegas.

Bugs

 * After talking with Keller, the dialogue option to pass a 7 INT/PER check pops up and does not work and always results in failure, despite having 7 Perception and 7 Intelligence.
 * After talking with Keller and passing the INT/PER check, if you choose to attack and kill Keller after he says you're under arrest when you return to Contreras the result and dialogue option will be the same as if you kept Keller alive and bribed him to play along and keep his mouth shut about the chem trafficking. If you kill Keller in this order you will not take a hit to your reputation with the NCR, and you will gain access to the stash and This Machine. Although it disables the ability to turn him into Lt. Boyd (This occurs as of patch #2).
 * Sometimes, even if you kill him without NCR reputation loss, the NCR will be hostile towards you. A fix for this is to reload to the save after you killed him but before the NCR went hostile and travel to the New Vegas Strip.
 * If you say that you will rat out Contreras, and then kill Keller, you will lose no reputation with the NCR.
 * Upon passing the Speech check to convince Keller you are merely seeking Price to purchase from him, you will gain no XP for doing so, unlike every other Speech check in the game.