By Debbie Emery - Breaking Celebrity News Reporter

The former prime suspect in the disappearance of missing Maryland woman Robyn Gardner is being sued by the insurance company that he took a policy out on her life with.

An American Express subsidiary has taken out a lawsuit against Gary Giordano, of Gaithersburg, to void the claim that he made in her name before the couple went on an ill-fated trip to Aruba in August 2011.

The suit was filed by the AMEX Assurance Company in federal court last week, claiming that the policy isn't legally enforceable because Giordano and Gardner aren't married or otherwise related, weren't business partners and didn't own property together, reported the Huffington Post.

It also accuses him of lying on insurance forms by identifying Gardner as his "partner" when the two actually had what the company calls a "casual and non-exclusive" relationship.

"You have to have an economic interest in the person" when taking out a policy, American Express spokeswoman Gail Wasserman said Monday.

As Breaking Celebrity News previously reported, authorities arrested Gardner's traveling companion, 51-year-old Giordano as he tried to leave Aruba last summer, after he reported Gardner had disappeared while snorkeling August 2. After a series of searches, neither Gardner's body nor any related physical evidence was recovered, spurring a judge last December to order Giordano freed.