Gary V. Giordano (Handout)

The Montgomery County man held in Aruba as part of a high-profile missing-persons case is no longer cooperating, authorities said Thursday night as they appealed to the public for help.

FBI officials also said that they are providing assistance to Aruban authorities and interviewing people in the United States, but declined to give details or say who was being interviewed.

PHOTOS: Robyn Gardner

The Aruban Public Prosecutor’s Office also released a photograph of the detained man, Gary V. Giordano, in an effort to bring in tips from people who may have seen Giordano on the island resort after he arrived July 31 with Robyn Gardner, 35, also from Maryland.

Prosecutors identified the pair by their initials, G.V.G. and R.G., as is their policy for cases in the stage of the legal process.

Robyn Gardner (Handout)

On Aug. 2, two days after the pair arrived, Giordano told local police that he and Gardner had gone snorkeling, he came ashore but she remained at sea, prosecutors said. Three days later, as Giordano tried to leave the island, police arrested him at the airport. He has been held since while police investigate what happened to Gardner.

“At this point in time, there’s discrepancies in his story, and we need to address them with him,” Aruban Solicitor General Taco Stein said in an interview this week.

Giordano has not been charged in Aruba. His attorney, Michael Lopez, has told the Associated Press and other media outlets that there is no indication his client did anything wrong.

“The last day of his stay in Aruba, we specifically asked Justice if they needed for him to stay a little bit longer,” Lopez told reporters, according to an ABC News report. “They didn’t answer it, and at the airport, they detained him as a suspect for murder… The current outside there is very harsh. It will take you away in minutes if you don’t watch out. And I think that’s what’s happened.”