Transcript for FBI investigating mysterious Caribbean disappearance of newlywed wife

We turn to a mystery at sea. A mom from Florida vanished after her husband said they got into some sort of boating accident near the Bahamas. The coast guard frantically searched for the missing woman and now the FBI is investigating and ABC's Linzie Janis last all the details. Reporter: Good morning to you, Dan. This couple from delray beach, Florida, were celebrating their recent marriage by sailing the caribbean. That's when he says there was a terrible accident. He was rescued and she wasn't. Now the FBI is checking out his story. This morning, the FBI investigating the mysterious disappearance of Florida mother Isabella Hellman who vanished while on a sailing trip with her husband Lewis Bennett, the newlyweds setting off from Cuba, the evening of may 14th but at 1:30 A.M. The coast guard getting a distress signal from the couple's boat. The initial report we had was that the catamaran vessel struck an unknown submerged object and gadge taking on water. Reporter: Three hours later they spot the overturned boat discovering Bennett 1,000 yards away in a life raft but no sign of his wife and the mother of their 9-month-old daughter. Bennett telling authorities he last saw Hellman at 8:00 P.M. She was piloting the catamaran wearing a life vest. He was going below deck to sleep. He says he woke up when the boat hit something. At that point Mr. Bennett investigated, looked for his wife, abandoned the vessel into a life raft and then called for assistance. Reporter: The coast guard scouring nearly 7,000 square miles of ocean, but calling off the search after three days and calling in the FBI. Many times when people present a story, the coast guard and the FBI then will go and look and see does the story match the reality, the damage to the boat, the timing when it allegedly occurred. They'll see if that fact pattern can even be corroborated. Reporter: The family of Isabella Hellman have declined to comment. So has the FBI. This is just a preliminary investigation at the moment. The FBI will then decide if it needs to be a full-blown criminal investigation but Bennett last said he was headed to Cuba to try to search for his wife on his own. We appreciate it. Thanks so much.

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