Transcript for Security guard in Costa Rica arrested in connection to American's murder

We turn to new developments in the case of the American woman murdered on vacation in Costa Rica and now learning of a possible motive as many ask how to be sure vacation rentals are safe. Reporter: We are learning new details about what happened to Carla Stefaniak. Authorities now giving a motive saying the attack was sexually motivated. This morning, the family of Carla Stefaniak devastated. It's too much for us. That's too much for us. Reporter: Trying to make sense of her brutal murder while on vacation in Costa Rica celebrating her birthday. Police arresting bismarck Martinez, a 32-year-old security guard who lived in a room near the airbnb rental where she was staying. They removed the listing from the site but listings for the complex are still active on other websites, one write-up touting 24/7 guard service for the safety of our guests and their property. It has temporarily closed the facility during the police investigation adding, it is deeply saddened and devastated by the tragic events and is fully cooperating with the authorities. But Stefaniak's murder now raising questions about the safety of vacation rentals. Welcome to the world of trips. Reporter: There is no screening process to become an airbnb host. Housekeeping services and security are negotiated between the host and guest. But there is no common vetting process. While most airbnb and other rental experiences go off without a hitch, there is a growing list of horror stories. Last month authorities say this couple from New Orleans died from carbon monoxide poisoning from a Mexican airbnb and it did not have a working detector and one Florida couple discovered they were being secretly recorded after finding a small camera hidden inside a smoke detector in their rental unit. That owner was sentenced to a year behind bars and banned from listing on airbnb for life. Experts say the key to a good experience is communication. Reach out to the owner before you rent, that way you know if you can reach out during your stay and get a feel for them so you can have a gut feeling about whether or not this is a good idea all before you ever decide to actually rent. Makes sense. Thanks, Eva. Now to the American tourist

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