Johnny John was the primary associate of Arty Atkins, who worked to steal Cecil Rogers's Tuba from a bank vault. A succubus attempted to suck out his soul, but he was saved by the Middleman and Wendy Watson. He later stole the tuba again, this time from Rogers himself, and in the process shot Rogers in the heart with a .38 snub nose revolver.
It was later revealed that both thefts had been orchestrated by Arthur Mendelson. Johnny John remained on guard on Mendelson's ocean liner to prevent any further attempts to steal the tuba, but he was downed by the Middleman's use of Twisted Stones.
Presumably, Johnny John was arrested alongside Mendelson by the FBI and Coast Guard for grand larceny.