Cole was promoted for Lieutenant in the US Marine Corp after he kills a lot of Japanese when his buddies were proud of him.
After the war ended, Cole returned to the USA as a war hero, joining the L.A.P.D. as a patrol officer. After showing extraordinary detective skills, he was promoted to a detective in the traffic division, partnered with Stefan Bukowski.
He gradually rose through the ranks of L.A.P.D. as time passed, being promoted to homicide, then even vice. Despite his abilities, however, he was demoted to arson after a public scandal, which his superiors claimed was a disgrace for the L.A.P.D.
Even after having his reputation tarnished, he was still decisive about solving a major insurance scam, which led to his death in a final showdown with the mobsters and corrupt L.A. officials behind the scam. His funeral was later attended by his partners and family. Roy Earle gave a eulogy, praising for Cole's actions and bravery in the war and the LAPD. Roy denounced a false accusation about Cole's affair with Elsa that made against him which angered Elsa in the progress. Jack Kelso tried to calm Elsa but she slapped his hand away saying "he calls himself a friend". Herschel Biggs, Cole's partner from Arson, told Jack that Cole was never his friend. Jack agreed but he told Herschel he was never his enemy. Herschel understood that Cole already knew that.
Cole Phelps similar to Elliot Ness & Dick Tracy because for his detective style to look like a minted detective for himself.
Cole Phelps' outfit Swords of Justice is similar to Phoenix Wright the Blue suit & Red tie for his own style.
- Cole Phelps is the third Rockstar protagonist to die in the conclusion of his game. The first being Daniel Lamb from Manhunt. And the second being John Marston from Red Dead Redemption.
- Cole's voice actor, Aaron Staton is married to Connie Fletcher (the voice actress of his wife, Marie Phelps) in real life. They both have children as well (Cole has 2 daughters and Aaron has a son).
- Cole can speak Japanese well, from his days in the war.
- His death is similar to Charlton Heaton's character in the 1974 film Earthquake.