Pacci's career as an NCIS Special Agent came to an abrupt and very tragic end when he was killed in the line of duty in April 2004, leaving the NCIS team and Gibbs completely devastated.
Not much is known about Pacci or where he came from but that he eventually joined NCIS, presumably working his way through the ranks before he became an official NCIS Special Agent.
Prior to dying, Pacci also investigated the disappearance of Petty Officer Third Class Carolyn Figgus but was ultimately forced to stop working on the case after it went cold due to any lack of possible leads or new evidence.
NCIS Season 1Edit
Pacci made his debut appearance in the Season 1 episode, Bête Noire (episode) where he participated in the rescue operation to save NCIS Medical Examiner Dr. Donald Mallard, Ducky's assistant, Gerald Jackson and NCIS Special Agent Caitlin Todd from a gunman.
After that, Pacci began investigating Navy Lieutenant Commander Hamilton Voss who had stolen ten million dollars before apparently dying in a car accident. He also came across a lead: a woman named Amanda Reed.
In UnSEALeD (episode), Pacci approached Gibbs, asking for help but Gibbs was forced to turn Pacci due to the fact that the main NCIS team were searching for escaped Navy SEAL Jack Curtin.
Accepting that, Pacci presumably headed off to investigate himself. He then arrived at a building and just as he was leaving, was subsequently shot in the neck.
Quickly bleeding out, Pacci headed to the elevator but not before swallowing an card from his camera, knowing that Gibbs and the main NCIS team would be called to the scene. He then collapsed in the elevator and died from blood loss with his killer (Amanda Reed who was in fact Navy Lieutenant Commander Hamilton Voss and who had faked her death to avoid being prosecuted) following him in and then disemboweling his remains as Reed desperately searched for the card so that she could destroy it.
Unfortunately, the alarm system went off, forcing Reed to flee while some local cops who had been called to the scene made the grim discovery and called NCIS upon learning that Pacci was an NCIS Special Agent.
Pacci's remains were brought back to NCIS and autopsied before they were brought to his family with his remains presumably being buried at a funeral that many of Pacci's NCIS colleagues including Gibbs and Kate attending with NCIS Director Thomas Morrow even giving a eulogy at the funeral too.
Eventually, the team tracked down Reed/Voss to a bar in D.C., Redd/Voss having befriended Tony.
In the ensuing confusion, Reed/Voss attempted to escape to avoid being arrested for the crimes she had committed as Voss but Gibbs had arrived there first and shot Reed/Voss dead, avenging Pacci.