Yankees star Brett Gardner's 14-year-old son Miller's cause of death confirmed as carbon monoxide inhalation

Miller Mack Gardner, the 14-year-old son of Yankees star Brett Gardner and his wife, Jessica, passed away as a result of 'lethal' levels of carboxyhemoglobin.

On March 23, Brett and Jessica announced their son's passing via a statement shared online, revealing Miller died 'peacefully in his sleep' on the morning of Friday, March 21 while the family were visiting a town on the central Pacific coast of Costa Rica.

The statement read: "Miller was a beloved son and brother and we cannot yet comprehend our life without his infectious smile. He loved football, baseball, golf, hunting, fishing, his family and his friends. He lived life to the fullest every single day.

"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.

"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."

Miller had been on vacation with his family when he died (Charleston Post & Courier)

The family didn't detail how Miller passed away, however, Director of the Organismo de Investigación Judicial (OIJ), Randall Zuniga has since confirmed the teen's cause of death has been ruled as 'exposure to carbon monoxide'.

He said in a statement shared by his press department with Crhoy.com: "The toxicology results are in and the carboxyhemoglobin test found a saturation of 64 percent. Concentrations above 50 percent are already lethal.

"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 added the other drugs tested conducted, 'including fentanyl and other substances' all came back 'negative'.

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

Miller's family have asked for memorial donations in his honor ( Mike Stobe/Getty Images)

The tribute continued: "Outside of school, his hobbies included golf, fishing, hunting, riding dirt bikes, and traveling to new places with his family."

It stated Miller's passing will leave a 'void' which will be 'felt for years' in the 'hearts of his family, friends, teammates, teachers, 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," it continued. "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 have asked for memorial donations to be made in his honor to The Make-A-Wish Foundation.

UNILAD has contacted Organismo de Investigación Judicial for comment.