Sam Bower was a friend of SSA Stephen Walker's from his days at the Behavioral Analysis Program. He appeared as an incidental character in the Season Twelve episode of Criminal Minds, "Unforgettable".
Sam was once a friend of Stephen's, having worked alongside him at the Behavioral Analysis Program. They were so close that they would often have dinners and friendly chats with their wives. The two were stationed in Russia for some time in a counterintelligence capacity, to investigate corruption in the national government, being assisted by dissident Dmitri Sobchek. Sam was primarily involved in cultivating human assets with an emphasis on Russian business graft and political corruption, posing as an American entrepreneur attempting to garner Russian capital. Eventually, in 2016, Sam went through an acrimonious divorce with his wife Lisa, and he subsequently had an estrangement with his son Zach, a college student. Despite this latest personal turmoil, he remained in close contact with Stephen, listing him as his emergency contact.
In the episode, Sam is attacked by Sara McLean, who injects him with stolen irradiated materials that make him come down with symptoms resembling those of a heart attack. Afterwards, he is brought to the hospital, where they contact Stephen to come see him. When Stephen comes to the hospital, Sam tells him about what happened to him. He was walking during lunch and on the way back to the office, he collapsed and was brought to the hospital. Then, Sam says that he felt a pinch in the lower back. When Stephen asks him to roll over, he realizes that he is exposed to radiation including himself and tells a nurse to call a hazmat team. When they arrive at the hospital, they scan Sam and find out that he has been contaminated with radiation.
The next day, Sam is seen mumbling in his sleep as Stephen watches him. Later, Stephen tells Sam that he is no longer present a risk of contamination to anyone. Then, Stephen tells Sam that he can fight this as he is strong. However, Sam tells Stephen that transfusions are not working, his liver is failing and asks him who poisoned him, to which Stephen replies that they don't know. Sam tells Stephen to promise him that he will find the person that poisoned him. Stephen tells Sam that he will call his ex-wife Lisa, but he tells him not to as he doesn't want her to see him in the hospital. Then, Stephen asks about Zach, but he replies that Zach is angry with him. Stephen tells Sam that he doesn't want him to be alone, but Sam replies that he is not alone as Stephen is with him. After the conclusion of the case, Sam is visited by Zach and later dies off-screen from the radiation poisoning.