"Something's happening out there. Something terrible..."
Detective Cal McGee is an incidental character who appeared in Legacy.
Little is known about McGee's personal life, other than he suffered from obsessive-compulsive disorder and his father was an officer in the Kansas City Police Department who was killed in the line of duty. Following in his father's footsteps, McGee rose to the ranks of police detective. However, he was assigned to watch over the residents of the city's slums (prostitutes, junkies, and vagrants) by his superior, Captain Al Wright, who was once his father's partner on the force, a fact that was presumed by McGee himself to be the sole reason he was still an officer. Eventually, his watch over the slums' residents gained him recognition when at least 63 residents mysteriously vanished. Under the assumption that it was because of his efforts, the police department gave McGee an award for his work. Sometime after, someone sent him a threatening letter, which stated that he didn't deserve the recognition. Deducing a pattern with the residents who disappeared, McGee personally traveled to Quantico and contacted the BAU in "Legacy", showing them his personal notes of the people living within his assigned area.
Hotch and JJ reluctantly go with him to Kansas City to discuss the matter with Wright, who remains adamant that all of the possible disappearances of the 63 people are a pure coincidence, as the case is difficult and they have no records of any of them. Since the BAU require being asked for help by local police, unless the case is federal, they can't do anything. When JJ discovers that the letter sent to McGee had been sent from Kansas City, Missouri, which is across a river but also across the state line, making the case federal, the rest of the BAU are called in. McGee then aids the team in asking around for potential suspects on the street. However, just as the search is coming up with nothing, the BAU spot a van driven by Steven Foster. When they try to question him, Steven tries driving away, but Morgan jumps in through the window, causing him to crash. After a brief interrogation, Steven reluctantly decides to give McGee and the BAU the address of the unsub, Charles Holcombe. After Charles is shot dead while trying to kill a would-be victim, McGee is last seen investigating the meat-packing plant Charles was using to kill his victims alongside Wright.