He maintained that the body still needed to be fingerprinted before they made an official announcement.
Authorities also say they have detained a suspect in the case.
Costa Rican authorities have discovered a body near the area where US resident Carla Stefaniak disappeared last week.
Espinoza added that authorities found stains in the Airbnb apartment where Stefaniak was staying that were "compatible with blood", though they are conducting further testing.
Relatives said Stefaniak was scheduled to come back to Florida the next morning, on November 27, but no one had heard from her in five days, and her family feared the worst. Stefaniak missed her flight home November 28, one day after she was last seen in a villa in San Antonio de Escazu outside the capital of San Jose. Burton flew back on the 27th, and Stefaniak planned to fly back the day after. They said the body was found almost 1,000 feet from the property and had signs of blunt force trauma to the head and injuries caused by a blade to the neck and upper extremities. We're going on six days not hearing from her.
"Hope is the last thing you've got to lose", she said.
Officials said immigration reports indicate Espinosa Martinez has an "irregular immigration status" in Costa Rica and has been in the country since June.
"'I'm just gonna go ask the guards to buy me a bottle of water.' He says that her phone died, and that's it", Burton said.
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The two texted each other via WhatsApp throughout the day Wednesday, Burton said, until Stefaniak suddenly stopped responding to her messages that evening. Her father flew down to Costa Rica on Monday afternoon.
The investigation is ongoing and officials said an active search is still ongoing. However, an Uber driver she scheduled to pick her up still showed up at 8:30 a.m. Jaime said.
"It was her birthday, and she loves to be on social media", Stefaniak's brother, Carlos Caicedo, told CBS News.
The night prior to her flight, Stefaniak took an Uber ride around the town and was dropped off at her Airbnb.
"At midnight Eastern time, Burton texted Stefaniak to wish her a happy birthday but did not receive a response", Gardner said.
"So we don't know if it's the guards, we don't know if it's the Airbnb guy, we don't know if it's both", said her sister-in-law April Burton. "We have received over 1,000 guests with wonderful reviews about the property and our service", Federico Jenkins said.
An attorney for the vacation rental facility from which Stefaniak disappeared released a statement to WFTS, saying the owners are also cooperating with the investigation and have temporarily closed the facility.
According to authorities, investigators raided his apartment, Apt.