When he’s gone, the news will shock them all, from the FBI to his family to the daughters of Roman Totenberg, who stand to inherit the instrument. They will ask how this once-promising, later penniless eccentric stole an 18th-century violin worth millions — and got away with it. After all, he was the only suspect when it was taken in 1980. As death approaches, Johnson, usually the loudest voice in the room, keeps his mouth shut. It is the fall of 2011. This has been his secret for 31 years. ... Johnson, who was never able to hold a job, a mortgage or a relationship, somehow accomplished something most everyone thought impossible: He played Totenberg’s Stradivarius in plain view until the end. ... He did this through chaos and control, by building an impenetrable wall between his past and present. Those who suspected Johnson of the crime lost track of him. Those who knew him during the last two decades of his life had never heard of the Totenberg theft. They just thought Johnson had an old violin. ... Experts estimate that of the 1,000 or so violins crafted before Stradivari’s death in 1737, about 500 survive today. ... Johnson was never meant to be a journeyman. At one time, he was thought by many, including his college teacher Joseph Silverstein — one of the great orchestral violinists of the 20th century — to be a dynamic player with considerable promise.