Over the years, Marks convinced Deveraux to sell her house and all of her assets while isolating herself from all of her family and friends. Stack said that threats were made against her and her family in order to keep the money coming.
"Jude believes that she signed a will," Stack said. "We're desperately trying to find that."
In an email to ABCNews.com, Deveraux said that her 2010 novel "Scarlet Nights" details how the fraudulent psychics work and how they exploit people for money.
"I worked with the police on the story, especially the few pages that tell about the way gypsies give people hope and how they cut them off from everyone. This is all done for money," Deveraux wrote to ABCNews.com.