Jack Curtin was a former Navy SEAL and a Petty Officer First Class who was jailed after being convicted of murdering his wife and a cable repairman.
Not much is known about his early life except for the fact that he grew up in foster homes and enlisted in the Marines when he was seventeen years old.
However, after being sentenced to imprisonment for the crime, Curtin later escaped from Leavenworth where he was being held and as such, NCIS were forced to reopen the case as well as put his young son, Kevin and his guardians, Kevin's grandparents who were also Curtin's deceased wife's father and mother from harm.
Curtin later broke into where his son was staying and tied up Agent Caitlin Todd who was on guard duty at the time before stealing her service weapon and radio before heading upstairs to see his son for one last time, intending to say goodbye.
Agent Timothy McGee who had been outside suspected something was wrong and later arrived in the house, freeing Todd who then alerted the authorities about what was going on.
Realizing that NCIS were onto him, Curtin fled the scene, hijacking a car in the process which both McGee and Todd shot at. While McGee's shots only damaged the car's back window, Kate, on the other hand was successful in injuring Curtin by using a shotgun she'd taken from one of the NCIS cars to fire back at him.
It was revealed that Kate's attempts had worked as Curtin was seen tending to his left arm which he had wrapped in a bandage, confirming Abby's theory that he was down to just one arm.
He had also discovered that his wife's lover was none than Mrs Foley, the wife of Commander William Foley, Curtin's former Commanding Officer but Curtin was presumably unaware of the fact that Commander Foley himself had been responsible for the deaths of both Mrs Curtin and the cable repairman.
Driven by a strong need for revenge, Curtin later found out Mrs Foley had been his wife's lover all along and attempted to kill her, only to realize that NCIS had arranged the entire thing and that "Mrs Foley" was none other than Kate whose service weapon Curtin had stolen to help him carry out his quest of seeking justice.
Curtin was eventually arrested and presumably cleared of the murder charge but it's possible that he was jailed for assaulting a Federal Agent and assault with a deadly weapon.
- Caitlin Todd- (tied up and stole her service weapon)
- Unnamed Driver- (forced him to get out of his car at gunpoint and then fled the scene)
- "Mrs Foley"/Kate Todd- (intended to kill but Kate, Gibbs and Tony stopped him from doing so)