MINNEAPOLIS (WCCO) – A Farmington, Minnesota, man was sentenced to 12 years in prison for defrauding elderly victims out of more than $1.3 million in cash, precious metals and coins.

Dennis Charles Helmer, 54, had pleaded guilty in September 2014 to targeting a 79-year-old stroke victim, a 99-year-old dementia patient and a legally blind octogenarian.

He falsely told his victims that his businesses, Wholesale Assets Worldwide and Best Price International, had more than 75 employees and $500 million in annual revenue. And he obtained a fake “Dun & Bradstreet Credibility Review.

Helmer had convicted three previous times for running similar schemes in Dakota and Hennepin counties, and he operated his coin fraud operation under the aliases, “Jeff Jones,” “Mr. Diamond” and “Dennis Dimon.

He was convicted of one count of mail fraud after a joint investigation by the U.S. Postal Inspection Service and the Minnesota Department of Commerce.

Earlier this month, a Roseville rare coin dealer was sentenced to six years in prison for running a similar coin fraud scheme.