Calling allegations that a Hawaii couple stole identities of dead babies for unknown reasons unique, a U.S. judge on Monday upheld a previous ruling to detain the pair without bail.

According to prosecutors, Walter Glenn Primrose and Gwynn Darle Morrison are the real names of the couple who have been fraudulently living for decades under stolen identities, Bobby Fort and Julie Montague. Prosecutors say Primrose spent more than 20 years in the Coast Guard, where he obtained secret-­level security clearance.

U.S. District Judge Leslie Kobayashi said the mystery behind why the couple lived under allegedly stolen identities for so long is what makes the case unique: “Because the real question is, why?”

Primrose and Morrison have pleaded not guilty to conspiracy, false statement in a passport application and aggravated identity theft. Prosecutors have suggested the case is about more than identity theft.

A search of the couple’s home in Kapolei turned up Polaroids of them wearing jackets that appear to be authentic KGB uniforms, an invisible ink kit, documents with coded language and maps showing military bases, prosecutors said.

Defense attorneys for the couple have said they took a photo wearing the same jacket years ago.

“Mr. Primrose’s lack of ownership and possession of the alleged KGB uniform even more strongly supports the inference that he and his co-defendant, are not, in fact, Russian spies, and that the photographs of them are more akin to dressing up in a costume, engaging in cosplay, or the like,” Assistant Federal Defender Max Mizono, who represents Primrose, wrote in a motion appealing a magistrate judge’s detention order.

He explained the invisible ink as a “toy purchased many years ago for entertainment,” and the other items to also be innocuous.

Kobayashi said she only considered the charges, and not “suspicions” but was concerned about the couple’s lack of ties to Hawaii.

Prosecutors also have mentioned existence of correspondence found in the home in which an associate believed Primrose had joined the CIA or had become a Bolivian terrorist.

“Stated otherwise, it is simply not feasible that Mr. Primrose is a member of the CIA, a Bolivian terrorist, and a Russian spy, all the while working at both the U.S. Coast Guard and a private employer and living a relatively low-key lifestyle in Kapolei for the last twenty years,” Mizono said. “In sum, the government should put its money where its mouth is, submit all this evidence to the Court, and let the Court ascertain the veracity behind its claims that Mr. Primrose is a Russian spy.”

After their arrests last month and while alone in a holding room at FBI headquarters in Kapolei, the couple made comments about espionage, prosecutors said.

Morrison told Primrose that “we have the protocols,” prosecutors wrote in opposing the detention appeal.

“The FBI knows that foreign intelligence services have protocols that they teach their agents and those recruited by their agents to follow if they are ever apprehended,” Assistant U.S. Attorney Thomas Muehleck wrote, adding that making such statements when they were only being asked about identity theft “is consistent with espionage.”

Muehleck said prosecutors are also concerned that Primrose used his stolen identity to obtain a private pilot’s license, which has been seized, and that he was stationed with the Coast Guard in Kodiak, Alaska, from 2013 and 2016 while Morrison stayed in Hawaii.

The two homes they purchased under the names Fort and Montague could be subjected to forfeiture, prosecutors said.

Primrose has been fired from his contractor job and his Coast Guard retirement pay has been suspended, Muehleck said.