|“||Even if he thinks he's finished, he still has a debt to pay.||”|
— Max at the end of his lecture
Max mentored Gideon and taught him everything he knew about profiling. One of Gideon's earliest cases was a bomber case, supervised by Max. As a prank for the new member, Max and the other investigators planted a list of the FBI director's whereabouts over the next 48 hours in the bomber's car for Gideon to find. When he found it, he rushed up 25 flights of stairs and interrupted a meeting between the director and the U.S. Attorney General in an attempt to save him. Max was also the profiler and one of the many people chasing Walter Kern, the Keystone Killer, who stopped killing at the end of the 80s. He is apparently famous for catching a serial killer called "The Boise Child Killer". Sometime during Gideon's training, Max became his mentor. Max moved to Philadelphia when he retired, where the Keystone Killer was active. After retiring, Max wrote the book Houses of Horrors: The Hunt for the Keystone Killer, which was released in 2006. He had apparently written at least one more book before that.
In 2006, Max gives out a lecture about his book at the J. Miller Bookstore. Soon afterwards, he receives another letter from the Keystone Killer, who is now back on the hunt. Still bitter over not being able to apprehend him in the 80s, Max becomes a temporary consultant for the BAU. Despite having some initial problems working with other people, they are eventually able to catch Kern as he is about to kill another victim and Ryan is allowed to make the arrest.
He was later mentioned in the episodes "Machismo" and "Nelson's Sparrow", and also the novel Killer Profile. In the latter, the unsub used one of Max's books, Serial Killers and Mass Murderers: Profiling Why They Kill, as a reference for his copycat murders. The serial killers written in the book were Jeffrey Dahmer, David Berkowitz, Ted Bundy, John Wayne Gacy, Aileen Wuornos, and Herman Kotchman, while the rampage killers were Richard Speck, Howard Unruh, Charles Whitman, and Byran Uyesugi.