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.

The death of Miller Gardner, the 14-year-old son of former New York Yankees outfielder Brett Gardner, was due to carbon monoxide inhalation, the Judicial Investigation Agency (OIJ) of Costa Rica said Wednesday.

Brett Gardner’s son died of carbon monoxide poisoning. Carbon monoxide is known as the “invisible killer” because it is a colorless, odorless, tasteless gas or liquid. Here’s how to protect yourself and your family from carbon monoxide poisoning while traveling.