Jonas T. Smith is a real-estate broker and criminal. He founded Krypton Island, which was renamed Kryptonopolis after his arrest for illegal activities.
Smith had committed a number of crimes previously, enough to get him a record with the FBI. ("Krypton on Earth")
He decided to set up Krypton Island as part of a scheme to swindle Superman into creating a series of diamonds out of coal, which he could then steal. During this time he took on the identity of Thor Kol. However, when he used his fingerprint, Superman recognized it from the FBI file and took him to justice, leaving Krypton Island to new management. ("Krypton on Earth")