London ( CNN ) -- In the early hours of March 22 this year , cruise ship worker Rebecca Coriam made a mysterious phonecall . No one knows who she spoke to , or what the call was about . Minutes later she hung up , walked away -- and apparently vanished without a trace . Six months later , her parents still have no idea what happened to their 24-year-old daughter on board the Disney Wonder ship as it sailed off the coast of California . And like the loved ones of scores of others who have vanished from cruises in international waters , there is little they can do to find out . While millions of people around the world take cruises every year , at least 168 people have vanished from cruise ships and ferries in international waters since 1995 , according to the International Cruise Victims Association . Maritime law states that crimes are to be investigated by police in the country where the ship is registered . So while Coriam , who is British , went missing off the coast of California , her case was taken up in the Bahamas , where the Disney Wonder is registered . Coriam 's parents , Mike and Ann , were shocked to learn that rather than American or British police boarding the ship to gather evidence , Disney and then Bahamian law enforcement were to handle the investigation . The Coriams flew to Los Angeles where they were shown CCTV footage of their daughter making a phone call in the early hours of the morning she went missing -- the only piece of evidence they 've been shown in the investigation into her disappearance , they say . `` We do n't know what was in the phonecall and when she finished the call she just walked away , '' Mike told CNN . `` That 's all we really know to this day . '' A single police officer from the Bahamas flew into town but failed to interview any of the roughly 3,700 passengers and crewon the cruise ship -- and that appears to be the extent of the investigation into their daughter 's disappearance , her parents say . Superintendent Paul Rolle of the Bahamas police told the UK newspaper Daily Mail : `` I have been in touch with the family and have no further comment . '' `` We get very little information coming back to us as to what the investigation has found out , and that 's partly because of the problems of where the ship 's registered , '' said Mike . Rebecca 's parents are demanding new regulations similar to a new U.S. law which allows the FBI and U.S. Coast Guard to investigate cases of missing U.S. citizens regardless of where the ship is registered . `` The law we want is what President Barack Obama signed up to last year in the U.S. , '' said Mike . `` We want the same in the UK and Europe and elsewhere . '' The Coriams have met with UK shipping minister Mike Penning , who has pledged to raise the issue with the International Maritime Organization -- but progress has been slow . `` It 's been absolutely awful , '' said Anne . `` We just miss her desperately now -- it 's the longest we 've ever gone without seeing her , and it 's not getting any easier at all . '' At the time of her disappearance a Disney spokeswoman said : `` We have been doing everything possible to find Rebecca Coriam including conducting multiple shipboard searches . In addition , we have been working with all of the appropriate authorities . Rebecca 's disappearance has been difficult for everyone at Disney Cruise Line . '' `` We 've been in close contact with the Coriam family , and we 're assisting them in any way we can . '' Mike blames the culture of cruise ships , and not Disney or the Bahamian police , for the lack of action over Rebecca 's disappearance . And with the recent news that the UK cruise line company Cunard is considering moving its ships ' registrations to a different country , even more cruise passengers could be exposed to the problems the Coriams have faced . With little more support than that of their own family , the Coriams say they are focused on finding out what happened to their daughter -- and preventing others from going through the same trauma . `` We 've got to find out what 's happened to her -- you do n't just vanish off of a ship with all those people , '' said Anne . `` We 'll keep on and keep strong for her until we find answers . ''
Rebecca Coriam disappeared from a Disney cruise ship in March . 168 people have vanished from cruise ships and ferries in international waters since 1995 . Missing persons at sea must be investigated by the country where the ship is registered . The U.S. Coast Guard has jurisdiction over all vessels that are not American flagged, but it doesn't investigate disappearances on foreign shores because they're considered national security issues.