(MANUEL ANTONIO, COSTA RICA) — High levels of carbon monoxide were detected in 14-year-old Miller Gardner’s hotel room, Costa Rican police revealed more than one week after the son of former New York Yankees outfielder Brett Gardner mysteriously died on a family vacation.

The carbon monoxide was discovered while conducting tests last week in Miller Gardner’s room at the exclusive Arenas Del Mar resort in Manuel Antonio, Costa Rican police said Monday.

Miller Gardner’s cause of death is not known and investigators are still waiting for final toxicology results.

“We are heartbroken by the tragic loss,” a spokesperson for the Arenas Del Mar resort said in a statement. “We trust that the forensic process will objectively, clearly, and conclusively clarify the causes of this unfortunate incident.”

“Out of respect for the ongoing judicial process and the family’s privacy, we will refrain from commenting on any unconfirmed hypotheses or possible causes,” the spokesperson continued.

Miller Gardner died in his sleep on the morning of March 21, according to the family.

The night before, the Gardners went out to dinner at a restaurant close to the resort, and they felt sick when they returned to the hotel, according to a Costa Rican source close to the investigation.

A hotel spokesperson said the staff “dispatched a medical team immediately, including a licensed doctor, which arrived to handle the emergency situation.”

“Miller was a beloved son and brother and we cannot yet comprehend our life without his infectious smile,” the Gardners said. “We are so thankful to all who have reached out to offer support and encouragement during this difficult time and we are confident our faith, family, and friends will help us navigate this unimaginable loss.”

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