Toxicology results have finally confirmed the cause of death of former New York Yankees star Brett Gardner’s son Miller.

Costa Rican officials announced Wednesday that the 14-year-old died from carbon monoxide inhalation while vacationing with his family in the country.

“The toxicology results are in, and the carboxyhemoglobin test found a saturation of 64%. Concentrations above 50% are already lethal,” Randall Zúñiga, director of the Judicial Investigation Agency, said in a press statement, per a local news outlet.

“In this case, the saturation percentage is higher, thus proving the police’s hypothesis that the death was due to exposure to carbon monoxide.”

In light of the toxicology results, Zúñiga said the case was now closed.

Miller was found dead at the Arenas Del Mar Beachfront & Rainforest Resort on March 21 after falling ill under mysterious circumstances.

“Out of respect for the ongoing judicial process and the family’s privacy, we will refrain from commenting on any hypotheses or possible causes,” the hotel told Page Six following Wednesday’s announcement.

“Our priority remains the safety and well-being of our guests and staff, and we reaffirm our ongoing commitment to the highest operational standards within our facilities.”

Local authorities revealed Monday that investigators had detected “high levels of carbon monoxide contamination” in the Gardner family’s hotel room at the resort.

At the time, Zúñiga noted during a virtual press conference that there was a “specialized machine room” next to their accommodations, “from which it is believed some form of contamination may have reached the guest rooms.”

However, the hotel denied the carbon monoxide theory the following day.

“The levels in the hotel room were non-existent and non-lethal. There was an error in this initial reporting,” the Arenas Del Mar Beachfront & Rainforest Resort claimed to The Post Tuesday.

The hotel insisted the high levels of carbon monoxide were detected in a “mechanical room that guests do not occupy” and not the actual guest room.

Still, staffers did close the room “out of an abundance of caution” while awaiting “conclusive results” to confirm Miller’s cause of death.

Authorities had previously speculated the teen died from an allergic reaction to food poisoning medication or from asphyxiation — but both hypotheses were later thrown out.

According to Dr. Kevin Gannon, who runs Manuel Antonio Urgent Care, there was “not much” first responders could do when they arrived on the scene to treat Miller.

“We responded to a patient without vital signs,” Gannon told People last week, explaining they performed “advanced life support CPR” for 30 minutes before he was “declared dead.”

Brett and his wife, Jessica, revealed their “unimaginable loss” in a statement shared by the Yankees on March 23.

The couple, who also shares son Hunter, said Miller “passed away peacefully in his sleep” after he and several other family members got sick during the vacation.

The Post confirmed Miller’s body has already been released to his family and funeral arrangements are underway.

A private celebration of life will be held in South Carolina, per Miller’s obituary.