Miller Gardner, teen son of ex-N.Y. Yankee Brett Gardner, died of carbon monoxide poisoning, Costa Rica says

San Jose, Costa Rica — Carbon monoxide poisoning was the cause of death of the teenage son of former New York Yankees outfielder Brett Gardner, authorities in Costa Rica confirmed Wednesday night.

Randall Zúñiga, director of the Judicial Investigation Agency, or OIJ,  said they tested the 14-year-old Miller Gardner for carboxyhemoglobin, a compound generated when carbon monoxide binds to hemoglobin in the blood.

When carboxyhemoglobin saturation exceeds 50%, it is considered lethal. In Gardner's case, the test showed a saturation of 64%.