The BAU collaborates with Agent Goldman, who is a part of the White Collar Crime unit of San Diego. Goldman has been trailing a con artist for a few years, and his suspect has changed MOs recently. He's never killed any of his victims until two nights ago in Miami. The victim was Carla Marshall, who was murdered in her home.
The unsub's specialty is investment fraud, and he targeted wealthy single women or wealthy men's wives. The team's profile of the unsub suggests that he needed to be control at all times. If something out of the ordinary happened, which he didn't plan for, that would cause him to snap and cause violence. He won't stop because it wouldn't be about the money anymore, but getting psychological satisfaction from the degree of control a killing would give him over another person's life.
The team discovers that the unsub has multiple investment websites under different identities, and he has so many different names to keep track of, he might have broken under that immense pressure. While with one of his clients/victims, the unsub can't recall which alias he was using, and kills the client after his mistake causes suspicions to arise. The unsub might be trying to get rid of all his aliases by killing his clients list, and thusly, all of the evidence that his aliases existed.
The unsub apparently settled in San Diego for over three years, which is suspicious for a con artist. He must have started a family during that time. Garcia tracks down his wife, Rebecca Hodges, and his son, J.D. Hodges. The unsub (William Hodges) is found trying to force his son into a car. He gives up his son to the BAU, but when Hodges reaches for something in his pocket, Agent Goldman, who thinks that the man is pulling out a gun, shoots him dead.