Miller Gardner -- the 14-year-old son of former New York Yankees outfielder Brett Gardner -- died from carbon monoxide poisoning, Costa Rican authorities have said.

Miller Gardner, the teenage son of New York Yankees alum Brett Gardner, died from carbon monoxide poisoning, Costa Rica officials confirmed. A new toxicology report found the 14-year-old South Carolina boy's body had carboxyhemoglobin level of 64%,

A toxicology report after his death found high levels of carboxyhemoglobin, an indicator of carbon monoxide in the blood, according to a statement from Randall Zúñiga, the director of the Costa Rica Judicial Investigation Agency. Miller Gardner’s test showed a saturation of 64 percent, he said, adding that anything over 50 percent was lethal.