According to Prentiss, Cooper served in a branch of the U.S. Armed Forces and was presumably an officer. After being discharged, he became a detective with the New York City Police Department. In his personal life, he had a wife and at least one child who is a toddler. At work, Cooper would take off his wedding ring and flirt with other women in the line of duty. However, this was presumably done to boost his self-esteem, as he was still loyal to his wife and would quickly backtrack if any of the women returned his advances. In May 2008, Cooper began investigating a serial killer who was shooting and killing random pedestrians in New York City. After four murders, the investigation was taken over by SSA Kate Joyner, who he had to report to.
Lo-Fi (Part 1)
Cooper is first seen with his partner, Detective Brustin, as Kate Joyner introduces them to the BAU, who was called in after a fifth murder. Cooper then explains to Reid Brustin's displeasure at having his case handed over to federal authorities. Then, he asks Prentiss to profile him, but she replies that won't happen. Cooper is next seen partnering up with Reid and Prentiss about the unsub's M.O. Later, Cooper is present with the rest of the precinct when the team gives out a profile on the unsub, who by that point was believed to be a group.
While staking out a subway, Cooper and Prentiss discuss about going undercover and acting like a couple, but Prentiss laughs it off and then profiles him. Later, they are both patrolling the streets when a hooded man shoots and kills a woman standing in front of an ATM machine. They pursue the shooter, with Cooper closest to him. When Cooper corners him in an alleyway, the shooter fires his gun, hitting Cooper, and an arriving Prentiss returns fire, killing him. Cooper survives the gunshot wound and he is last seen being taken into an ambulance.
Mayhem (Part 2)
At the end of the episode, Cooper is seen in the hospital with Brustin when Prentiss comes into the room. Brustin leaves the two alone and they start talking. Cooper apologizes to Prentiss about Kate, who had died in an SUV bombing. He then asks Prentiss about Hotch, who was injured in the bombing, and she says that he can't fly for a while. When Prentiss gives Cooper tickets to great seats for a New York Mets game, he says that most people mistake him for a Yankees fan, and Prentiss says that she is not most people. They both say goodbye to each other afterward.