Despite a successful practice, by 1983 he was in financial difficulties from bad real estate investments and gambling debts.[89] Becoming involved in a counterfeiting scheme, he printed $6 million in U.S. 100-dollar bills, some of which he stored in ice chests buried in the back yard of a house he owned and rented out.[54][90][91] Charged along with five others, he served two-and-a-half years of a five-year sentence at the Federal Correctional Institution, Texarkana.[53] Upon his release in 1986, he regained his dentistry license but struggled to rebuild his practice.[38] In 1995, he was hired as a dentist at the Louisiana State Penitentiary, initially as a contractor. At the time, the dental clinic in the prison was in chaos; many dentists refused to work there and inmates were often unable to make appointments.[38] Cannon reorganized the dental program with great success and was soon hired as a full-time employee.[92] Warden Burl Cain, impressed with Cannon's work with the dental program, put him in charge of the prison's entire medical system.[38] Cannon remained the resident dentist at the penitentiary, where inmates typically call him "Legend".[38][93]A