Aug. 17, 2011 -- Authorities are investigating an insurance policy on Robyn Gardner purchased before she traveled with Gary Giordano to Aruba as a possible motive in the disappearance of the missing Maryland woman.

The investigation into the insurance policy on Gardner for as much as $1.5 million -- which names Giordano as a beneficiary -- has been confirmed exclusively to ABC News by a law enforcement source.

Gardner, 35, has been missing for two weeks, since reportedly snorkeling with Giordano, 50, off of an isolated beach on Aug. 2. The two traveled together from Maryland to Aruba on July 31. She is now presumed to be dead by Aruba police.

The FBI is also investigating the American Express insurance policy.

Giordano was ordered this week to remain in an Aruban jail for another 16 days while police investigate what they say are "serious inconsistencies" in his story. Investigators have found apparent gaps in time between when witnesses saw the pair on the beach and the timeline Giordano gave when he reported Gardner missing.

Though he has not been charged with a crime, Giordano remains the only suspect in the case.

Giordano, court documents show, is a man trailed by a history of domestic violence.

Erratic Behavior Surrounding Disappearance

Surveillance video from local businesses place Giordano and Gardner at the Rum Reef Bar & Grill in the Baby Beach area of the island before Gardner went missing, a law enforcement source told ABC News. Restaurant staff said that Gardner seemed woozy while the two ate; Giordano later told police they'd been drinking vodka at the Marriott before dining, and that she'd taken sleeping pills earlier in the day, the source said.

Video also shows Giordano in his rental car parked in the back of the bar and restaurant. The Toyota Rav-4 had tinted windows, so no one else in the vehicle can be identified. Giordano parked the car in the back parking lot twice; he told police that he wanted to park in the shade, the law enforcement source told ABC News.

The car was cleaned once Giordano returned the car to the Star rental at Aruba's airport, so police were unable to investigate the vehicle, according to law enforcement. The rental agents said that they didn't notice anything unusual when it was cleaned.

Investigators have also said that they had trouble identifying Giordano in surveillance video because he frequently changed his toupees.

At approximately 6:02 p.m., after Gardner went missing, the law enforcement source said that Giordano is also seen in surveillance video, tapping on closed shutters of the bar -- seemingly making his presence known. At approximately 6:20 p.m. he headed to the back kitchen of the bar and told someone to call police.

Authorities said that that they found blood on a rock behind the dive shop at the Rum Reef Bar & Grill, which is the last place the two were seen together.

Investigators also told ABC News of Giordano's other erratic behavior at the time of the disappearance -- including that he left the search early to get some sleep at his hotel.

Three days after the search for Gardner began, Giordano got within feet of leaving the country before he was stopped at Aruba's airport, after passing through security and U.S. customs -- where he told customs he had to change flights because of weather, and inexplicably told officials that his travel companion was "taking another flight." When arrested, authorities say Giordano was drenched in sweat.

These developments were considered so significant that on Tuesday Judge Monique Yarzagaray ruled that Giordano be detained for double the time the prosecution originally requested. While in jail Giordano will undergo day-long interrogation each day, in which his lawyer can only be present before and afterward.

Aruba police will now have more than two weeks to mount a case against Giordano, based on evidence collected from witnesses, surveillance video, personal cell phones and laptops, and other information collected by police and the FBI, which is helping with the investigation.

Federal agents searched Giordano's Gaithersburg, Maryland, home over the weekend, seizing cell phones and laptops. The home was known to have been equipped with surveillance cameras and signs warning visitors that video and audio of their visits would be recorded, according to neighbors.

Authorities in Aruba will now be focusing the search for Gardner on an area away from the beach where she went missing, but within the area where she could've traveled in that 4 p.m.to 6 p.m. timeline. The FBI is sending bloodhounds, while Curacao and Aruba riot cops and volunteers will comb the area.

Police are asking members of the public that may have information about Gardner's disappearance to call 011-297-582-0695 and leave their tip and contact information. The Natalee Holloway Resource Center, which is also helping with the case, has set up an American tip line at 407-237-2295.

This story has been updated with new information from law enforcement.