Before his arrival in Rapture, the man who would become Subject Delta was a deep sea diver who conducted an investigation of the many ship and submarine disappearances in the Atlantic Ocean southwest of Iceland. While surveying the area in an advanced diving chamber he accidentally discovered the hidden city. He was accepted into Rapture, becoming somewhat of a celebrity for his heroics and nicknamed "Johnny Topside" by articles in the Rapture Tribune.
However, Andrew Ryan did not trust his story and was convinced that he must be a government agent sent to spy on Rapture. Stanley Poole, a journalist who had written a story on "Johnny Topside" turned him in to Ryan, who immediately had him incarcerated at Persephone Penal Colony and erased all documentation of him from the city.