Miller Mack Gardner, the 14-year-old son of Yankees player Brett Gardner and his wife, Jessica, died from ‘lethal’ amounts of carboxyhemoglobin.

Brett and Jessica confirmed their son’s death on March 23 in an online post, claiming Miller died ‘peacefully in his sleep’ on the morning of Friday, March 21, while the family was visiting a hamlet on Costa Rica’s central Pacific coast.

The statement read, “Miller was a loving son and brother, and we cannot imagine our lives without his contagious grin. He enjoyed football, baseball, golf, hunting, fishing, his family, and his friends. He lived each day to the utmost.

“We are grateful to everyone who has reached out to give their support and encouragement at this terrible time, and we are certain that our faith, family, and friends will guide us through this unthinkable loss.

“Our prayers go out to Miller’s teammates and friends, as well as to all other families who have lost a child far too soon, as we share their grief.”

The family did not say how Miller died, but Randall Zuniga, Director of the Organismo de Investigación Judicial (OIJ), has verified the teen’s cause of death was ‘exposure to carbon monoxide.’

In a statement provided to Crhoy.com by his press staff, he stated, “The toxicology findings are in, and the carboxyhemoglobin test revealed a saturation of 64 percent. Concentrations beyond 50% are already deadly.

“In this case, the saturation percentage is higher, thus proving the police’s hypothesis that the death was due to exposure to carbon monoxide.”

He claimed that all other narcotics tested, ‘including fentanyl and other substances,’ came out ‘negative.’

The Charleston Post & Courier published Miller’s obituary one week after his death, describing him as an ‘active 8th grade student’ who was a member of the football team at the middle school and junior varsity baseball team, as well as the school Honor Roll.’

The touching tribute went on: “Outside of school, his hobbies included golf, fishing, hunting, riding dirt bikes, and traveling to new places with his family.”

Miller’s death will leave a ‘vacuum’ that will be ‘felt for years’ in the ‘hearts of his family, friends, teammates, instructors, coaches, and others.’

“The Gardner family will forever cherish the places they visited, the people they met, the friends they made, and the memories they created together,” she said. “Miller’s time here with them was brief, but his spirit will carry on forever through those who were impacted by the way he lived..

Miller’s family has requested memorial donations to the Make-A-Wish Foundation in his honor.