A Costa Rican doctor has divulged new details about Brett Gardner’s son Miller Gardner’s final moments.

Dr. Kevin Gannon, who runs Manuel Antonio Urgent Care, spoke to People on Monday about the 14-year-old being “clinically dead when [first responder] arrived” to treat him.

The medical professional said his team “perform[ed] advanced life support CPR” at Costa Rica’s Arenas Del Mar Beachfront & Rainforest Resort for 30 minutes on March 21.

A Costa Rican doctor shared insight into Brett Gardner’s son Miller’s last moments.

The 14-year-old was “clinically dead” when first responders arrived to treat him. TikTok / zoe

“A licensed physician, a nurse and an ambulance first response driver” showed up to treat him. TikTok / JK

However, he noted, “There was not much we could do for him.”

Gannon explained, “We responded to a patient without vital signs, and he had no vital signs when we arrived. And we do not have records of him at all.”

Similarly, he told Us Weekly that a “licensed physician, a nurse and an ambulance first response driver” from his team “responded immediately” to the emergency call — and “called authorities” when the teen was “declared dead after 30 minutes.”

The teen was not showing any “vital signs” at the time.

First responders performed CPR for 30 minutes. Instagram / Ken

Gannon acknowledged that, while he doesn’t “know what caused” Miller’s death, his family members were experiencing “gastrointestinal symptoms.”

He shared with The Post that his team “could not verify a cause of death,” calling the situation “very confusing.”

Brett’s son’s autopsy results will reportedly take up to 90 days due to a “hike in homicides” as “drug gangs battle for territory,” Juan Pablo Alvarado Garcia, a representative for Costa Rica’s Judicial Investigation Agency explained to the Daily Mail on Wednesday.

Miller died last week while on vacation with his family.

This took place at Costa Rica’s Arenas Del Mar Beachfront & Rainforest Resort. Arenas Del Mar Beachfront & Rainforest Resort

“There was not much we could do,” Dr. Kevin Gannon said. TikTok / zoe

The retired New York Yankees player and his wife, Jessica Clendenin, revealed their loss in a March 23 statement via the team’s X account, writing that their youngest child “passed away peacefully in his sleep.”

The couple, who also share 16-year-old son Hunter, added, “He was 14 years old and has left us far too soon after falling ill along with several other family members while on vacation. We have so many questions and so few answers.”

They “have not been able to pick the body up yet because they are still waiting for all the procedures required by the American embassy here,” Garcia told the outlet.

The medical professional said he doesn’t “know what caused” Miller’s March 21 death. TikTok / zoe

Miller and his family members suffered food poisoning prior to his death. WireImage

The night before Miller’s death, he and his family members suffered from food poisoning, according to local authorities.

Asphyxiation has been ruled out as his cause of death — despite initial reports claiming so — with Miller perhaps suffering an allergic reaction to the medication used to treat his food poisoning.

However, Gannon told The Post that “it is very, very rare for a patient to eat food and go that long without a reaction” or to have “allergic reactions to normal gastrointestinal medications.”

There was no indication of recreational drugs or alcohol contributing to his death, according to Garcia.

Miller was on a vacation with his parents and 16-year-old brother Hunter. Instagram / Hunter Gardner

Brett shared his loss on the New York Yankees’ X account on March 23. MLB via Getty Images

He noted that the early asphyxiation theory occurred because “when … agents showed up at the scene, they observed the body with vomit in the mouth and nasal passages.”

Miller’s girlfriend, Zoe Williams, penned an emotional tribute via TikTok last week.

“I just wish I could’ve said goodbye or talked to you or even given you a hug for one last time,” the high school student wrote. “I love you more than anything and I’ll never be able to get over your loss.”