"I add voices until the choir is big enough to sing me into heaven when I die. It's necessary. Don't you see? The overture is just beginning, Ms. Winters."
- – Karl Mueller's thoughts during court ordered scan (inadmissible)
Karl Mueller was a convicted multiple murderer and suspected serial killer. Following his conviction he was sentenced to have his mind wiped and have a new personality given to him.
Karl Edward Mueller was found guilty of killing two lurkers and one security officer aboard Babylon 5 following a bench trial by Ombuds Wellington. Mueller was subsequently sentenced to the "Death of Personality." Following a telepathic scan of his mind conducted by Talia Winters before the scheduled mindwipe, Ms Winters privately confirmed to Security Chief Garibaldi that Mueller had indeed murdered dozens of persons from numerous races prior to coming to the station (though such information is of course inadmissible under Earth Alliance law.) Karl was clearly insane, raving to Talia about "needing to add voices to his choir to sing him up to heaven when he died."
While being transferred to the Medlab for the mindwipe, he escaped and hid in Downbelow. Later he tried to use the alien healing device to heal his wounds received when he escaped, but was killed by Dr. Laura Rosen when she sucked his life-force from him through the machine.