Colker, 39,was found dead on one of the Caribbean island's secluded beaches on Sunday. An autopsy report said she also suffered an "extensive" skull fracture and was asphyxiated.
A physician's assistant in Atlanta, Colker was vacationing with her 62-year-old husband Brian Melito when they were attacked, police said. Melito managed to escape and was not injured.
James did not say why Benjamin targeted the couple. But cops zeroed-in on the suspect after witnesses reported seeing Benjamin “begging persons on the beach for money,” he said.
“That is why he became our chief suspect,” James said.
Corky Siemaszko is a senior writer for NBC News Digital.
Cassandra Vinograd is a Senior Writer and News Editor. Before joining NBC News, she worked as a London-based correspondent for The Associated Press and specialized in politics, foreign affairs and defense.
Vinograd previously worked as an editor for The Wall Street Journal in Brussels and London.
She has reported extensively from Afghanistan and on West Africa and the Middle East.