Dominick Wayne was a Captain in the United States Navy and a member of JSOC.
NCIS Season 10
NCIS Season 11
In Past, Present, and Future (episode), Dominick Wayne is seen talking with NCIS Special Agent Leroy Jethro Gibbs about the whereabouts of Benham Parsa. Wayne wants to make amends, but doesn't want to reveal where Parsa is. Gibbs tells him that he should do what's right, because he won't get another chance to redeem himself.
Later on in the episode, seconds after shooting both of Lawrence Walters' bodyguards once in the chest with a sniper, Brotherhood of Doubt member Henry Coldwell is confronted by Wayne. He states that he can't do the wrong thing anymore & upon saying this, he pulls out a knife, intending to attack &/or (attempt to kill) him. However, Coldwell immediately fights back & they struggle for the knife for a few minutes.
Upon hearing them fighting, Gibbs bursts in to find Coldwell, dead, on the floor after being stabbed by Wayne, but he also finds Wayne on the floor, still alive but bleeding from his wounds from also being stabbed in the abdomen by Coldwell during their fight. He tells Gibbs to "do it".
Gibbs then goes to the sniper rifle & looks through the scope, witnessing Brotherhood of Doubt member Tomás Mendez being in protective custody by FBI Agent Tobias Fornell. He hesitates at killing Mendez for a second because his close friend is right there with him. He then decides to go through with it, shooting Mendez in the chest, killing him instantly, but the bullet also hits Fornell in the ass, making him fall to the ground, groaning in pain & agony.
Gibbs then looks back at Wayne, only to find that he has bled to death from his injuries.