Joseph "Joe" Keller Jr. is a serial killer introduced in the final three episodes of The Mentalist. Known by others as "Lazarus", he is a highly superstitious psychopath who murdered over ten people and stole their blood to perform blood magic.
Keller keeps his dead father, Joseph Keller Sr.'s body in his closet and believes he can use the blood to bind his father's soul to his body and keep him there forever. It is later discovered that his father, Keller Sr., was also a serial killer. Obsessed with trying to communicate with his father's spirit, he kidnaps a self-proclaimed psychic, Gabriel Osbourne, and murders him upon discovering that he is fake, carving the words fake into his arm. To lure him out, Patrick Jane pretends to be a psychic and broadcasts himself over the television and radio. Keller takes the bait and calls into the radio station using his alias, "Lazarus". The FBI tracks the call, but discover that the phone was rigged so they still had no idea were to find him. Keller then, abducts Jane and locks him in his basement, trying to force him to communicate with his father. When Keller leaves, Jane discovers Keller Sr.'s body and formulates a plan. Jane turns on the gas and places a wad of chewing gum on a light-bulb so when Keller returns, the house explodes. However, Keller manages to escape and is bent on revenge. He kidnaps Dan Glover, the radio host and murders him after calling the FBI with his phone and demanding to talk to Jane. Rick Tork unknowingly tells Keller that Jane is getting married to Lisbon, so Keller hurries to the Marriage License office and finds out that Emily Hamilton will be the judge. To avoid Keller, Patrick and Teresa move their wedding location to a secret area, however Keller hides in Emily's trunk, arriving at the secret location. Keller prepares to ambush the happy couple, but is surprised by the FBI and arrested.
- Two unnamed homeless people
- Unnamed sex worker
- Two unnamed exchange students
- Donnie Putnam
- Megan Brooks
- Ree Osbourne
- Gabriel Osbourne
- Susan Herman
- Dan Glover
- He usually takes a fingernail from the left hand of each of his victims.
- He used to go fishing with his father.
- He took the blood of his victims to speak to the spirit of his dead father.