A source told The Associated Press that Gardner's companion Gary Giordano sought to claim the policy two days after reporting her missing.
According to that source, Giordano purchased a $1.5 million American Express Travel Insurance policy shortly before he left for Aruba and that the accidental-death benefit covered only the length of their short trip.
The source did not have authorization to publicly release the information and agreed to speak with the AP only on condition of anonymity.
Meantime, police in Aruba have discovered racy photos of Giordano and Gardner on Giordano's digital camera. Authorities are trying to determine when those photos were taken.
Giordano is in custody in Aruba while police continue to search for the 35-year-old woman from Frederick, Maryland.
Giordano, a 50-year-old business owner from Gaithersburg, Maryland, traveled to Aruba with Gardner on July 31 and reported her missing two days later, saying she disappeared while the two were snorkeling.
He initially assisted the search but was detained at the airport as he tried to leave Aruba. Authorities said they had found discrepancies in his story.
Giordano, a twice-divorced father of three sons, has denied any wrongdoing through his attorney.
A judge ruled Monday there is enough evidence to hold him for at least 16 more days on suspicion of involvement in Gardner's presumed death. The woman's body has not been found and Aruban authorities on Thursday were preparing for a new, large-scale search of the island for her remains or other evidence.
The Associated Press contributed to this report.