Jason Paul Dean was a decorated Lieutenant of the US Army Rangers. After being dishonorably discharged from the army, he joined Colonel Merton Bell's First Defense PMC as a mercenary whilst secretly working for the Reynosa Cartel. He was responsible for the deaths of Special Agent Lara Macy and Colonel Bell himself.
After his discharge from the US Army Rangers, Dean, a Lieutenant, joined a mercenary firm, First Defense PMC, owned by Colonel Merton Bell. After his release from Mexican custody, Bell engaged in a quest to have revenge against the man who sent him to prison: NCIS Special Agent Leroy Jethro Gibbs. While his lawyer kept Gibbs occupied in Washington, Bell started to gather information on Gibbs as part of his plan. This lead him to meet with Paloma Reynosa, head of the Reynosa drug cartel, who believed Gibbs had killed her father twenty years previously. They formed a partnership and began developing an elaborate scheme to have revenge on Gibbs.
When the evidence against Gibbs was uncovered, Bell sent Dean to kill Special Agent Lara Macy who had known about the murder but had covered it up, believing it to be a just killing. Dean arranged for Macy to be placed in Gibbs's jurisdiction so as to send him a message. Later, Bell gathered several of his men and headed to Mexico to kill Michael Franks and his family.
However, Paloma wanted to use Franks to a different aim and sent her own men to capture him. Not trusting Bell, she had turned Dean and, during the confrontation between Bell's men, her men and Franks, Dean killed Bell by shooting him and decapitating his corpse while also recovering the finger that Franks lost in the fight.
When Gibbs arrived and found all the men dead, except Franks who had escaped, Dean captured him as he was standing over Bell who Gibbs actually thought was Franks.
Shortly thereafter Dean returned to Washington, DC accompanied by several members of the cartel, having sent a text message to Gibbs earlier, asking if he was safe.
NCIS had been alerted to Dean's impending arrival and Agents DiNozzo, David and McGee were dispatched to apprehend Dean and his companions, triggering a gunfight between the Agents and Dean and his gang although Dean was left enraged at the ambush, believing that Gibbs had double-crossed him although NCIS had simply discovered Dean was heading to America by accessing Gibbs's phone records. In the process, Dean was shot and killed by DiNozzo.
- Special Agent Lara Macy- (stabbed to death, then set on fire).
- The following were killed during the Mexico shootout:
- Colonel Merton Bell- (shot in the back and then decapitated post-mortem).
- Matthew Moore
- Anthony Jones
- Douglas Williams
- Viewers would recognize Dylan Bruno from his role in the cancelled TV series, "Numb3rs" where he played FBI Agent Colby Granger.