Two weeks ago, Brett Gardner was left with a devastating mystery: What caused the sudden death of his youngest son Miller on their trip to Costa Rica?
“He was 14 years old and has left us far too soon after falling ill along with several other family members while on vacation,” the former New York Yankees outfielder and his wife Jessica Gardner said in a statement shared to the team’s X account March 23. “We have so many questions and so few answers at this point, but we do know that he passed away peacefully in his sleep on the morning of Friday, March 21st.”
As messages of support and sympathy poured in, so did calls to put the pieces of this tragic puzzle together. Now, Brett, Jessica and their 16-year-old son Hunter have been given an answer. According to NBC News, Costa Rica’s Judicial Investigation Agency revealed on April 3 that toxicology results determined that Miller died of carbon monoxide poisoning.
However, uncovering the cause of death took time.
On March 24, Costa Rica’s Judicial Investigation Agency informed NBC News the late teen’s body was found in a hotel room in the resort district of Manuel Antonio.
“We are deeply saddened by this loss, and our hearts go out to the family during this incredibly difficult time,” the Arenas Del Mar Beachfront & Rainforest Resort said in a statement obtained by the outlet. “The factors that led to this tragic incident are unknown, and we are fully cooperating with authorities as they investigate. We remain committed to supporting our guests and staff, prioritizing their well-being and safety, while respecting the privacy of those affected.”
At the time, agency official Juan Pablo Alvarado Garcia told NBC News that Miller appeared to die by asphyxiation following “a possible intoxication after apparently ingesting some food.” He added the Gardner family became ill after eating at a nearby restaurant the day prior to the child’s passing and that they’d been treated by the hotel’s medical team.
After examining Miller’s body at the hotel, Alvarado Garcia continued, it appeared he had asphyxiated on his own vomit. However, the agency noted this was a preliminary cause of death as authorities were awaiting the results of autopsy and toxicology reports.
But the very next day, Alvarado Garcia backtracked and said it seems Miller didn’t die from asphyxiation. After consulting with a pathologist, he told NBC News in a March 25 statement, “it was preliminarily ruled out that the cause of death was due to asphyxia, due to the fact that at the time of the inspection of the body, no anomaly was observed at macro level in the respiratory tract.”
As a result, Alvarado Garcia added, samples were sent to a laboratory for analysis of the histology, toxicology and neuropathology, and a study was requested at a local university.
As for how the agency initially came to the preliminary findings before then backpedaling?
“When our agents showed up at the scene, they observed the body with vomit in the mouth and nasal passages,” Alvarado Garcia explained to the Daily Mail in an interview published March 26. “So they provided a preliminary report saying it could have been asphyxiation due to the vomit. We went with that version because the night before the family went to dine outside the hotel where they were staying, and they all started to feel sick when they returned. But once there was a deeper examination with the autopsy, the doctor did not find any abnormalities in the respiratory tract.”
Still, it seemed like it would take some time before the Gardners learned how Miller died.
“We’re having a hike in homicides as these drug gangs battle for territory and every one of them needs an autopsy,” Alvarado Garcia noted to the outlet. “I can confirm that an autopsy has been carried out on Miller. But the full analysis and results, as in every one of them, will take at least two to three months due to these constant killings causing a backlog of cases. That’s the reality.”
But just days later, the family got a possible explanation. According to NBC News, Costa Rica Judicial Investigative Agency General Director Randall Zuñiga said during a March 31 press conference that tests carried out in the family’s hotel room showed high levels of carbon monoxide contamination and suggested that Miller could have died from inhaling the gases. He added that the room was next to a “specialized machine room” that may have caused the contamination. However, Zuñiga noted authorities would have to wait for the results of the toxicology report to confirm the cause of death, and the hotel agreed.
“We understand the concern has grown and to clarify the high levels of carbon monoxide were in a mechanical room that guests do not occupy,” Arenas Del Mar Beachfront & Rainforest Resort spokesperson Dana Cohen told People April 1. “The levels in the hotel room were non-existent and non-lethal.”
While the spokesperson alleged “there was an error in this initial reporting” and that they would “await for conclusive results to confirm the cause of this unfortunate death,” the public information officer for the Costa Rica Judicial Investigative Agency told NBC News it would not respond to the hotel’s accusation amid the investigation.
However, they didn’t have to wait long for the results as the agency revealed days later that the toxicology report confirmed Miller’s cause of death was carbon monoxide poisoning. According to NBC News, the agency noted that a carboxyhemoglobin test was done and that a saturation of 64 percent was found when 50 percent is considered lethal. The agency added that “a very specific layer that forms when a person dies from carbon monoxide poisoning or gas inhalation” was also found on Miller’s organs during the autopsy.
In addition, the agency said a drug analysis was done and came back negative.
In an April 4 release obtained by NBC News, the Ministry of Health announced its investigation into what happened at the hotel.
Now, the Gardners and the sports community will continue to honor Miller’s legacy—with the New York Yankees paying tribute on Opening Day March 27.
“Miller was a beloved son and brother and we cannot yet comprehend our life without his infectious smile,
his parents wrote in their March 23 statement. “He loved football, baseball, golf, hunting, fishing, his family and his friends. He lived life to the fullest every single day.”
To learn more about the Gardners and the investigation into Miller’s death, keep reading.
Miller and his brother Hunter were raised in South Carolina.
Despite Brett Gardner spending his entire MLB career as a member of the New York Yankees, the outfielder and his wife Jessica Clendenin Gardner—who tied the knot in 2007—kept their sons Hunter and Miller largely out of the public eye in South Carolina.
Still, they occasionally stepped out in support of their dad’s career, attending the CCandy Children’s Clothing Line Launch at MLB Fan Cave in New York in 2013.
Miller was known to live “life to the fullest every single day.”
In a statement announcing his tragic death, Miller’s family described the 14-year-old as having an “infectious smile” and someone who “lived life to the fullest every single day.”
He was similarly remembered by the New York Yankees in a March 2025 statement, who emphasized Miller’s “outgoing and feisty personality.”
Miller was following his father Brett’s footsteps.
Like his dad, Miller was athletic, though in addition to baseball, he also took up football, golf, fishing and hunting. In a TikTok post he shared earlier this year, he emphasized his love for football by sharing photos of himself on the field, adding, “Miss it.”
Miller made an impact on the New York Yankees.
In a March 2025 statement by the Yankees confirming Miller’s death, the organization—for whom Brett played from 2008 to 2021—remembered the teen for the “spark in his eyes” as well as a “warm and loving nature.”
The team continued in their statement, “It wasn’t just Brett who literally grew up in this organization for more than 17 years—so did his wife, Jessica, and their two boys.”
The Gardner family is still looking for answers after Miller’s sudden death.
In a statement shared by Brett’s former team, the outfielder and his family shared that after Miller and others had fallen ill while on vacation, the 14-year-old passed “peacefully in his sleep the morning of Friday, March 21.”
“Miller was a beloved son and brother,” they wrote, “and we cannot yet comprehend our life without his infectious smile.”
And amid their grief, the Gardner family expressed how they are still trying to determine what happened. As they added in their statement, “We have so many questions and so few answers at this point.”
U.S. Embassy in Costa Rica confirms why the Gardner family was in the country.
The day after Brett and Jessica revealed that Miller had died, the U.S. Embassy of Costa Rica told Inside Edition that the family was vacationing in the Central American country for spring break at the time of his death.
The Embassy also confirmed that it was in discussions with the Gardner family about transporting Miller’s body back to the U.S.
Costa Rican officials release Miller’s preliminary cause of death.
One day after Brett and Jessica announced the sudden passing of Miller, Costa Rican officials said the teenager likely died from suffocation after possibly ingesting a toxic substance.
“Preliminarily, apparently the manner of death would be by asphyxia after a possible intoxication after apparently ingesting some food,” an Organismo de Investigación Judicial spokesperson told NBC News in a statement translated from Spanish. “At the moment it is a death under investigation and is awaiting the results of the autopsy, as well as the analysis of the Toxicology Section, to determine the exact cause of death.”
Miller’s cause of death as suffocation is ruled out.
However, authorities soon ruled out suffocation as his cause of death, because they did not find any obstruction in his airways.
They shared instead that Miller—as well as his parents and sibling—had fallen ill on March 20 after returning to their hotel from a restaurant, agency spokesperson Juan Pablo Alvarado Garcia told NBC News March 25. Hotel medical staffers treated all four family members before Miller’s body was found in his room the next morning.
The investigation is ongoing and pending medical test results.
The resort where Miller died releases a statement.
Two days after the Gardner family announced Miller’s death, the Arenas Del Mar Beachfront & Rainforest Resort where the family was vacationing in Costa Rica shared their condolences.
“We are deeply saddened by this loss, and our hearts go out to the family during this incredibly difficult time,” a representative for the hotel said in a March 25 statement to People. “The factors that led to this tragic incident are unknown, and we are fully cooperating with authorities as they investigate.”
The resort added, “We remain committed to supporting our guests and staff, prioritizing their well-being and safety, while respecting the privacy of those affected.”
The hotel also denied responsibility for the Gardner family getting sick at a nearby restaurant hours before Miller’s death.
“The family did not eat at any of Arenas Del Mar’s restaurants for lunch or dinner the previous day,” the resort’s rep continued. “Additionally, on March 14th, we had an inspection by the Health Ministry in which the hotel passed with a 98.5 out of 100.”
A Costa Rican official provides multiple major updates.
The day after the resort where the Gardner family was staying spoke out, Juan Pablo Alvarado Garcia, a spokesperson for Costa Rica’s Judicial Investigation Agency (JIA), confirmed that Miller’s autopsy results will be delayed by months due to high crime in the area.
“We’re having a hike in homicides as these drug gangs battle for territory,” he told DailyMail.com, “and every one of them needs an autopsy.”
He added, “I can confirm that an autopsy has been carried out on Miller, but the full analysis and results, as in every one of them, will take at least two to three months due to these constant killings causing a backlog of cases. That’s the reality.”
Alvarado Garcia did confirm, though, that there was no indication Miller’s death was a result of recreational drugs or alcohol.
Though the results will be delayed, the official explained that, since “all the samples necessary” had been taken for Miller’s autopsy, his body “can be repatriated to the United States,” however, the Gardner family has been held up by the U.S. Embassy in Costa Rica’s processing of their request.
New York Yankees pay tribute to Miller.
During their Opening Day 2025 festivities March 27, Brett’s former team took a moment of silence to honor Miller.
During the tribute, players stood with their hats removed along the edge of the baseball diamond at Yankee Stadium while a picture of Miller smiling was shown on the big screen. Accompanying the snap were the words “Remembering Miller Gardner.”
Investigators say toxicology report confirms cause of death
Miller “may have died from inhaling” carbon monoxide, according to the general director of Costa Rica’s Judicial Investigation Agency Randall Zúñiga, who said in a March 31 press conference that “high levels of carbon monoxide contamination” were found within the family’s hotel room.
Noting that a “specialized machine room” was located next door, Zúñiga said authorities believe “some form of contamination may have reached the guest rooms, potentially causing the incident.”
“Nonetheless, the initial investigative findings indicate that the incident was due to this contamination, with levels as high as 600 parts per million detected—when the appropriate level in this case should be zero,” he continued, adding that officials will “wait for the final results from forensic toxicology” before releasing Miller’s cause of death.
Those results were soon revealed. According to NBC News, the investigative agency announced on April 3 that the toxicology report determined that Miller died of carbon monoxide poisoning.
In a carboxyhemoglobin test, the agency continued, a saturation of 64 percent was found when 50 percent is considered lethal. The agency added “a very specific layer that forms when a person dies from carbon monoxide poisoning or gas inhalation” was also found on Miller’s organs during the autopsy.
In an April 4 release obtained by NBC News, the Ministry of Health announced its investigation into what happened at the hotel.
(E! and NBC News are both part of the NBCUniversal family).
This story was originally published March 30, 2025 at 6:00 a.m. PST.
