Miller Gardner, a 14-year-old son of longtime player Yankees Brett Gardner, died of carbon monoxide poisoning, while he was on vacation with his family last month last month, Costa Ratican authorities said on Thursday.

The report on toxicology after his death has determined the high level of carboxyhemoglobin, the indicators of carbon monoxide in the blood, according to a statement by Randalla Zúñige, director of the Costa Rare Agency. Miller Gardner’s test showed a 64 percent saturation, he said, adding that more than 50 percent is deadly.

Mr. Zúñiga said other tests were carried out, including drug tests, but everyone was negative. He said that an autopsy report found that the signs of carbon monoxide poisoning on the organs were added that the case could be considered closed.

Miller and his family were staying at the Costa Rica resort. The family was published last month published through Yankees that Miller died on March 21 “after he became ill with several other family members while on vacation.”

“He died calmly in his sleep,” the family said.

Authorities said the family was in Manuel Antoni, a resort on the center of the quiet coast of Costa Rica.

The authorities said At a press conference Wednesday that the family room at the resort was next to the rooms with machines and said that pollution may have come to that.

The settlement where the family remained, Arenas del Mar Beachfront & Rainforest Resort, did not respond to the commentary request after the results of toxicology.

The family said that Miller “loved football, baseball, golf, hunting, fishing, family and his friends.”

Brett Gardner, 41, played for Yankees for his entire career in the main league from 2008 to 2021.

He played the left and the central terrain and was part of a team of championship at the 2009 Warkee World Series. Until 2019, he was the last remaining Yankee of that team, who last won the title.

A fast left -hand player, led the league in stolen bases in 2011, and is triple in 2013. His lone season arrived in 2015. For his career, he hit .256 with 139 home runs.

He finished his last ride on the Yankee Stadium in 2008.

Mr. Gardner and his wife Jessica live in South Carolina. They have another son, Hunter, who is 16 years old.

Jonathan Wolfe contributed to reporting.