Hostel security guard arrested after American woman's body found

A security guard at the hostel where an American woman was staying during her last night in Costa Rica has been arrested in connection with her death, local authorities said Tuesday.

Carla Stefaniak was last heard from on Nov. 27, the night before her 36th birthday, her family told ABC News. The Miami resident traveled to Costa Rica on Thanksgiving Day to celebrate her birthday with her sister-in-law, April Burton, but decided to stay an extra day after Burton returned to Florida on Nov. 27, the family said.

Late Tuesday, Stefaniak's family confirmed that a body found decomposing in a wooded area about 1,000 feet away from her hostel in San Jose indeed was hers.

Bismarck Espinoza Martinez, a 32-year-old Nicaraguan security guard who lived in the room next to Stefaniak's at the hostel, has been arrested after testimony he gave investigators didn't match surveillance footage or other witness statements, Walter Espinoza, director of Costa Rica's Judicial Investigation Department, told reporters on Tuesday. Martinez had been in the country since June, Espinoza said.

Authorities had said earlier this week the body "preliminarily corresponds" to Stefaniak. An autopsy determined the cause of death as "stab wounds around the neck and extremities," Espinoza said. The body also had a blunt force trauma injury to the head.

Investigators had studied surveillance footage from the area where Stefaniak was staying, near the Juan Santamaría International Airport in San Jose, and compared it to witness statements, Espinoza said.

The testimony from Martinez was "incompatible to reality," Espinoza said. Martinez was living in apartment No. 7, while Stefaniak was staying next door in apartment No. 8. Blood was discovered in her room.

Stefaniak's family and friends last spoke to her on the night of Nov. 27 right before her phone died around 9 p.m., according to a timeline the family provided to ABC Tampa affiliate WFTS.

A couple hours before, Stefaniak had sent a message to a group chat on WhatsApp saying it was raining heavily and that the power went out, describing the situation as "Super Sketchy."

While FaceTiming with a friend around 7:20 p.m. that night, Stefaniak told him that she was thirsty, according to the timeline. When he suggested that she boil some water, she told him that all she could find was a skillet and said that she was going to ask one of the security guards to buy her a bottle of water, since it was raining, the family told WFTS. It's unclear if she had contact with one of the security guards.

The owner of the hostel told Stefaniak's family that she had checked out with all her belongings at 5:10 a.m. on Nov. 28, according to the timeline provided to WFTS. Stefaniak's flight wasn't until 1:30 p.m. that day, and the family said it was unlikely she would check out early for no reason. There were no security cameras on the property to verify the hostel owner's claim, the family told WFTS.

An Uber driver who had driven Stefaniak from the airport to the hostel on Nov. 27 -- after she dropped Burton off for her flight and returned their rental car -- told the family she'd asked him to pick her up the next morning around 8:30 a.m. and take her to a shopping center, but she never showed up, according to the provided timeline. That Uber driver also had taken Stefaniak on a city tour of San Jose after she checked into the hostel, the family told WFTS.

The U.S. Department of State had said in a statement to ABC News Tuesday that it was aware of the reports of a missing U.S. citizen and that an "unidentified body" had been found but did not comment further due to privacy concerns.