Deveraux provided millions of dollars to Marks over a nearly two-decade span, but the author claims she was supposed to get the money back, Schwartz explained.
"The question is when do you start asking for your money back?" Schwartz said. "If you give a million here and are supposed to get it back, and you give another second million the next year, when do you start getting buyer's remorse? That's a question we have and will ask Ms. Deveraux."
Schwartz said "overzealous" investigators approached a number of witnesses and told them they believed Marks cheated them and would try to get their money back.
"So now, they are saying what the government wants them to say," he said.
One "victim" filed a sworn affidavit saying he had not been swindled — but instead was a satisfied client of Marks' sister, Victoria Eli, who was his "personal life coach" for 12 years, the Sun-Sentinel reported.
ABC News' Christina Ng and Molly Riegger contributed to this report.