Darryl McCauley, 45, pleaded guilty to 27 counts of larceny over $250, three counts of forgery, embezzlement and other charges, reports the Boston Globe. At one point, McCauley wrote out a check for $3 million to himself from Cook's account.
McCauley served as Cook's business manager from the early 1990s until December 2008. He began siphoning Cook's funds into his personal accounts beginning in 2004.
The former corrections officer must serve another 10 years of probation after his release from jail. He must also make restitution to Cook, 38.
McCauley and Cook had the same mother, Donna Cook, who died in 2006. The actor has not commented on McCauley's sentence.