Blood test revealed a carbon monoxide saturation level of 64% in Gardner’s system. Levels above 50% are typically fatal.

Officials in Costa Rica confirmed Wednesday that the official cause of death for 14-year-old Miller Gardner was carbon monoxide poisoning.

Brett Gardner and his wife Jessica remembered their late son, Miller, who died during a trip to Costa Rica, in a touching obituary published by the 'Post and Courier' on March 29.