Lateef Mir was a member of the Brotherhood of Doubt. One of the earliest members of the terrorist group, he had managed to kill various journalists for their cause. He also was a chameleon, or someone with an extreme level of skill at disguising themselves.
Lateef Mir was arrested and placed on the Destroyer Niagra for terrorist activities, presumably due to information supplied by the then-deceased leader of the Brotherhood of Doubt, Benham Parsa. However, he alongside Edwin Smith (a Canadian who was previously unaffiliated with the Brotherhood) eventually escaped from the Niagra with the help of civilian contractors under the employ of disgraced Mexican Minister of Justice Alejandro Rivera, enlisting their aid in trying to assassinate MCRT team leader Leroy Jethro Gibbs (whom they had a mutual hatred for). After stealing a raft and making it to a restricted beach, Mir killed Edwin Smith, and eventually disguised himself. Having anticipated that NCIS would likely track him by photo recognition, he also hired a mercenary named Dar Tareen to act as a decoy, presumably also supplying him with one of the three unregistered glocks. When Dar Tareen failed to assassinate Gibbs, he eventually confronted Gibbs himself inside the latter's then-recently deceased father's garage and entered a fight with him. Ultimately, he got crushed by Jackson Gibbs' car falling on him.
Presumably, Mir never informed Rivera that he had a decoy pose as him in the initial assassination attempt, as Rivera reacted as though Mir actually was killed when his plans were revealed to have fallen apart and he ended up exposed.