Based on Sara Kuszak's description of her kidnapper's car, police arrested a local man whose clothing was covered with blood. He was not immediately charged.
"He saw the woman and kidnapped her," said Lt. Angel Ocasio. "He didn't take anything. He stole her life."
The man was located because the FBI picked up a signal from the victim's cell phone, which he was carrying, investigating officer Arsenio Rodriguez said. Kuszak's fiance had called the FBI, but the department turned the case over to local police.
The suspect told police that he was covered with blood because his brother owns horses and one of them had been cut, Rodriguez said.
Kuszak, who moved to Savannah, Georgia, from San Francisco about five years ago, arrived Tuesday night in Puerto Rico, where she met up with her fiance and several friends.
"She was looking forward to the rest of her life with her fiance and her unborn baby," her friend Matt Daniel said in a phone interview from Georgia. "I'm just devastated. I don't know who would do something like that."
Kuszak, who worked on sailboats and part-time in real-estate and catering, was five months pregnant, friends said.
She and her fiance, Cheshire McIntosh, met several years ago on a South Pacific island where she was vacationing and he was sailing a yacht, said another friend in Georgia, John Everette.
"That's how two young, attractive people met," he said. "She dropped her life in San Francisco ... to be with Cheshire and live this free life of sailing on the seas. She was a rolling stone."
Kuszak apparently was going to visit some friends whose yacht was at a marina in Fajardo, in eastern Puerto Rico, marina spokeswoman Frances Rios said. After she was kidnapped, Kuszak called a marina employee on her cell phone from the trunk of the car, Ocasio said. The employee then called 911.
It was unclear why Kuszak did not call 911 directly, but she may not have known that the same emergency number used on the mainland is also used on this U.S. Caribbean territory.
Police would not release a transcript of the employee's 911 call because the case is under investigation.
About an hour after receiving the call, police found Kuszak's partially clothed body in a field.