During a routine mission, both Marines were captured by Colombian insurgents who demanded a ransom of two million dollars in exchange for their safe return. But even though the CIA paid the ransom, both were supposedly killed by poison; it was revealed that this story had been faked, presumably to stop Canton's superiors from getting to the truth.
Canton was the agent assigned to pay the money but got greedy and left the Marines to die. To ensure his secret was kept safe and well aware that NCIS were investigating, he killed Major Kidwell by embalming the Marine while he was still alive and even pretended to be the Marine's C.O. while hoping it would enough to keep NCIS happy.
He later returned to Colombia to ensure that the embalming of Major Craig Peary went ahead which would further cement the story of the Marines being killed in active duty but was stopped by Agents Leroy Jethro Gibbs, Anthony DiNozzo, Caitlin Todd and Canton's own partner, Gonzales who attempted to reason with Canton but was killed after Canton shot him in the heart, asking for Gibbs instead.
Gibbs then gave into Canton's demands and having abandoned his gun, listened as the rogue Agent told him how he had kept the two million dollars for himself and had gone to play Colonel Walsh in the hope that his "unflattering" portrayal of both Kidwell and Peary would end the NCIS investigation for good.
Gibbs taunted him by saying that Canton sounded just like his ex-wife but the second that Canton raised his gun, Kate and Tony emerged from the corner, shooting.
Although it isn't shown, it's implied that Canton died during the gunfight and as such, NCIS were successful in reuniting Major Peary with his family.
Canton is a ruthless and greedy agent only concerned with getting and keeping any kind of money for himself. He has gone beyond a point where even simple reasoning doesn't work with him.
He cares little for the lives of others and often disposes of them once they've either outlived their usefulness to him or if they're becoming a pain.
He is even willing to kill innocent people just to make sure his guilty secret doesn't emerge and will often pose as other people to convince others everything is alright which also enables him to keep an eye on the investigations.
Canton may also be a narcissist as he attempted to shoot Gibbs when the older man insulted him.
- Lt. Colonel Walsh- (impersonated.)
- Anthony DiNozzo- (impersonated, later attempted to kill, failed, was later shot by DiNozzo and Kate Todd.)
- Major Jim Kidwell- (had him embalmed while he was still alive, killing him instantly.)
- Major Craig Peary- (held hostage, attempted to kill.)
- Gonzales- (shot in the chest, killing him instantly.)
- Leroy Jethro Gibbs- (attempted, failed.)
- Caitlin Todd- (attempted, failed.)