The group was presumably first mentioned during the Season 10 finale episode, Damned If You Do where Agents Anthony DiNozzo, Timothy McGee and Ziva David were tasked with finding the killer of Navy SEAL, Chad McBride.
It was later revealed that Mendez was actually working for the Brotherhood all along and that Gibbs had shot Mendez to stop him from setting off another bomb by means of his his cell phone.
The attack succeeded, resulting in the deaths of four people while leaving Delilah badly injured and later permanently paralyzed from the waist down.
A while later, Gibbs confronted Parsa, only for the terrorist to escape.
Angered, Gibbs soon ordered his team to launch a full-scale manhunt for Parsa with NSA analyst Eleanor Bishop leading the charge.
In Monsters and Men, the NCIS team finally captured Parsa, only to later discover that Parsa had allowed himself to be captured in the hope that he could complete a suicide mission while intending to kill Bishop but Gibbs later arrives at the holding cell and was able to shoot Parsa fatally, saving Bishop's life while ending the crisis once and for all.
With Parsa dead and most of the Brotherhood's members also dead or imprisoned, it's presumed that the Brotherhood of Doubt has been completely dissolved and as such, is no longer an active threat to NCIS and other federal agencies.
In addition, most of the members ended up arrested based on intel supplied by Parsa immediately prior to his death, although one of them ended up freed by Rivera via contacts so they could target Gibbs for assassination, as they both had a mutual hatred for Gibbs.
- Benham Parsa- leader, deceased.
- Tomás Mendez- Deceased.
- Henry Coldwell- Deceased.
- Fu'Ad Hansur- Deceased.
- Hayat Parsa- Unknown.
- Vernon Dale- Imprisoned.
- Dominick Wayne- Deceased.
- Victor Cheng- Imprisoned.
- Erin Pace- Imprisoned.
- Yusef Ryder- deceased.
- Bashir Malik- Imprisoned.
- Lateef Mir- Deceased.
- March 2007, Cairo, Egypt: Bus Bombing in Cairo, Egypt
- Thirty unnamed people (killed by Parsa).
- July 2008, Indian Ocean: Sabotage of a French Ship
- Fifteen unnamed people (killed by Parsa).
- November 2012, Bahrain: Hostage Crisis at the Luxury Hotel in Bahrain
- Twenty unnamed people (killed by Parsa).
- Two unnamed journalists (killed by Mir).
- Chad McBride (held captive and beaten to death by Parsa in Fuma, Arizona; decapitated post-mortem).
- Washington D.C. Hotel Bombing (three fatalities; committed by Parsa).
- Leroy Jethro Gibbs (attempted twice, failed both times).
- Lisa Pierway (strangled to death by Coldwell).
- Anthony DiNozzo (attempted by Coldwell).
- Ziva David (attempted, failed).
- Lawrence Walters (attempted to blow up twice by Tomas, failed).
- Two unnamed bodyguards (both shot once in the chest by Coldwell).
- Dominick Wayne (stabbed by Coldwell, later died from his wounds).
- Daniel Coyne (shot to death by a drone operated by Parsa).
- Yusef Ryder (blown up by Parsa).
- Drone Attack on the Conrad Gala:
- Six unnamed people (killed).
- Twenty-two unnamed people (survived).
- Delilah Fielding (survived, left permanently paralyzed).
- Unnamed man (killed by Mir).
- Edwin Smith (strangled to death by Mir).