It is feared that the couple were killed in the kidnapping in Grenada

On Sunday, inmates Ron Mitchell, 30, Abita Stanislaus, 25, and Trayvon Robertson, 19, managed to escape from their cell in St. Louis. George in Grenada.

During their escape, they hijacked a luxury yacht docked in the capital and began heading towards St. Petersburg. Saint Vincent and the Grenadines, located north of Grenada in the Caribbean Sea.

The owners of the luxury yacht, husband and wife Ralph Hendry and his wife Cathy Brandel from Virginia, USA, are believed to have been killed on board by escaped prisoners.

Ralph Hendry's sister, Soline Desmarais, told Fox 5 DC that the couple lived on the boat during the winter months and arrived in the tropical island nation two weeks ago. The plan was for them to stay for another week.

– When one of the boat's neighbors went to bed, he noticed that the ship was there, but in the morning, when the boat owner woke up, they were gone, Solen Desmarais tells the channel.

“I want to believe they are alive”

But the couple's bodies have not yet been found, and Desmarais still clings to hope that they are alive.

– Why do I assume that someone died without a body and DNA. I have to think positively. I want to believe they're alive, she told Fox 5 DC.

The police quickly searched for the three fleeing men, and it is possible that the trio could be arrested only three days after their escape.

Grenada police say they have sent senior investigators and technicians to St. Vincent to investigate the suspected murders on the boat.

The US State Department is also involved in the case.