Updated

U.S. Virgin Islands police said Tuesday that they have sought more than one search warrant for the 47-foot Siren Song catamaran belonging to Ryan Bane in connection with the disappearance of his U.K. girlfriend, Sarm Heslop – but the court denied them each time.

"The Virgin Islands Police Department sought a search warrant for the Siren Song on multiple occasions, but was denied by the courts," department spokesman Toby Derima told Fox News. "Ryan Bane, through his attorney, refused to have any search conducted of the vessel. We will continue to pursue all legal means to obtain a search warrant for the vessel."

For months, the department had not answered questions from Fox News regarding the possibility of a search warrant. And in late July, Heslop's parents pleaded with Bane to voluntarily allow a "full forensic search" of the vessel.

Sarm Heslop was reported missing in the early morning hours of March 8. A search by land, air and sea failed to find her.

MISSING SARM HESLOP: PARENTS OF UK WOMAN WHO DISAPPEARED IN US VIRGIN ISLANDS ASK FOR MORE HELP FROM BRITISH GOVERNMENT

Bane’s attorney has said the Coast Guard team performed an "on-site inspection of the vessel and an on-sight interview without limitation," but USCG officials said that they had been "denied full access" to the vessel and issued citations.

Without a warrant, Bane is under no obligation to voluntarily allow police to search his boat – and through his attorney he has denied any involvement in Heslop’s disappearance. He has not been named a suspect or accused of wrongdoing.

However, experts say it’s unusual for investigators to fail to obtain a search warrant in this situation. In fact, it should have been one of the first steps along with interviewing witnesses and reviewing video, according to David Katz, a former senior special agent with the Drug Enforcement Administration and the CEO of Global Security Group, a private investigation and security firm.

"It may not even center on [Bane]," Katz told Fox News Tuesday. "She went missing from the boat. I want to search the boat and find out, was there something? Maybe there was someone else on the boat, someone snuck on the boat?"

And on occasions when search warrants are denied, investigators have the ability to gather more information, present it to the judge again and seek another warrant, he said.

"They have enough probable cause, I think," Jerry Forrester, a former FBI agent and private investigator who has worked extensively in the Caribbean, told Fox News three weeks after the woman’s disappearance. "She’s missing, and she was on that boat... They’re just not doing their job."

On Tuesday, he said it was "strange" that a judge would turn down a warrant request, especially more than once.

"If the boat belonged to Joe Blow, or the boyfriend, or even her, but she didn't go missing from the boat, maybe then they wouldn't be able to get a search warrant," he said. "But she went missing, probably, from the boat. There's enough probable cause there to get a search warrant."

The U.S. Virgin Islands Department of Justice did not immediately respond to a Fox News request for comment on the denied warrant requests.

US VIRGIN ISLANDS MISSING SARM HESLOP: PARENTS ‘WANT, NEED AND DEMAND’ ANSWERS 5 MONTHS AFTER DISAPPEARANCE

Heslop, 41, was reported missing by her boyfriend, Bane, 44, around 2:30 a.m. on March 8. Police told him to contact the U.S. Coast Guard if she had fallen off his 47-foot catamaran, the Siren Song. He did so around 11:45 a.m., and Heslop has not been seen since the night before, when she and Bane went to a St. John bar, 420 to Center, near where his catamaran was moored. And police have said they could not confirm whether Heslop returned to the boat after being seen leaving the bar with Bane.

The timeline of events and Bane’s past criminal history could have also helped investigators obtain a search warrant, Katz said.

The booking photo from Bane's 2011 domestic violence arrest. (Oakland County Sheriff's Office )

"His story does not make sense," he said. "After she went missing, he was told to do X, Y and Z. He did not do that for an extended period of time."

In 2011, Bane was jailed after assaulting his then-wife, Corie Stevenson on their way home from a wedding. She told Fox News in March that when they got home after the night out drinking, he slammed her face into the ground, chipped her tooth and "basically choked [her] out."

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For Heslop’s friends and family, they've been left with heartbreak, questions and few answers.

"Over the past five months we have endured a living hell trying to piece together what may have happened to our daughter," Brenda Street and Peter Heslop wrote in a letter to U.K. Secretary of State Dominic Raab earlier this week, asking for increased involvement from British investigators.