(AREA) -- Federal prosecutors are recommending 17 1/2 years in prison for a Michigan man who collected $2 million by promoting himself as a law expert who could win freedom for inmates across the country. John Wilson of Yale is returning to Detroit federal court Thursday, six months after pleading guilty to fraud and a tax crime. Assistant U.S. Attorney Sarah Resnick Cohen says Wilson was a "wolf in sheep's clothing" who targeted poor, vulnerable families whose loved ones were in prison. He admits duping 2,100 victims by offering to get inmates released through research and a successful appeal. The 57-year-old Wilson doesn't have a college degree. The scam went on for a decade. Cohen says Wilson also has a history of impersonating a doctor and a sheriff.