— -- Gladys Makori's son arrived home for Christmas in a casket.
Griffin Gutwa appeared to be a fit and healthy 18-year-old freshman embarking on his dream of becoming a neurosurgeon, Makori, 49, told ABC News in an exclusive interview.
But that dream ended days before Christmas, when Gutwa died on board Delta flight 1687, leaving behind a family grappling for answers.
Gutwa, who came to the United States in 2004 by way of Mombasa, Kenya, was a devout deacon at his Minneapolis church and soon followed his cousin to sunnier pastures at the University of San Diego, where relatives said he was studying to be a doctor.
Gutwa, known by the nickname "Babu," which means "grandfather" in Swahili, led a very fit and disciplined life, Makori said. There was no indication anything was wrong with him physically, she added.
“He has never tasted alcohol,” Makori said. “Never smoked, nothing. He was a good Christian boy.”
But on Dec. 22, Gutwa closed his eyes to take a nap on his flight from San Diego to Minneapolis-St. Paul.
He never woke up again.
Makori arrived at the airport at just after 6 p.m. on Dec. 22 to meet her son, she said. But when she got there, she was told the plane was delayed.
“We were told to come back at 8 o’clock,” she said. “We weren’t told why.”
Makori returned to the airport two hours later, this time with her husband, Gideon Gutwa, and their other children. When they pulled up to the terminal, they were met by police, Makori said.
“They asked, ‘Are you Griffin’s parents?’” she recalled. “We said, ‘Yes.’”
Makori said they were told to park, and then officials pulled the parents aside.
“I asked, ‘What happened? What happened?’ and they said, 'Griffin died on board,'” Makori said through tears.
The flight from San Diego took off without any issue.
Griffin Gutwa settled into his seat, and when the snack cart rolled by, he asked the flight attendant for warm water, declining any food, Makori said police told her. He then dozed off.
But an hour and a half into the flight, Griffin Gutwa started having trouble breathing, Makori said police told her. A fellow passenger noticed and called for help.
The flight crew then asked passengers on the plane if they had any medical training, Makori said police told her. A psychiatrist and two nurses responded, and tended to Griffin Gutwa, who by this point wasn't breathing, she said.
One of the professionals commenced CPR and the pilot diverted the flight to the nearest airport -- Sioux Falls, South Dakota, Makori said police told her.
Paramedics met the plane on the ground and attempted to perform "lifesaving measures" before he was pronounced dead at 5:52 p.m., Sioux Falls police spokesman Officer Sam Clemens confirmed to ABC News.
In a statement to ABC News, Delta said: "On Dec. 22, the flight crew of Delta flight 1687 from San Diego to Minneapolis/St. Paul diverted to Sioux Falls following a customer medical emergency on board. The flight attendants used their training and engaged medical professionals on the flight to assist in the situation, and paramedics met the flight upon landing at Sioux Falls."
Based on preliminary findings from an autopsy, Griffin had an enlarged heart condition known as cardiomegaly, according to the Minnehaha County Coroner’s Office. However, Griffin's cause of death is still pending.
A quest for answers
Since she was told of her son's passing on board the flight, Makori said she's learned little of what happened in midair from Delta.
"There's a lot of questions I don't know," she said. "It's shocking [the airline] have not called yet to give us any information."
She added: "I want the Delta people to call me. They haven't called as a sign of courtesy to say, 'Sorry for your loss.'"
Delta told ABC News that one of its representatives reached out to Griffin Gutwa's family and that the airline was continuing to reach out.
Makori later told ABC News that there was a voicemail message left with her brother-in-law "late evening" on New Year's Day but said she didn't know of any other interaction with the airline since her son's death.
But beyond that, Makori said she wants to understand how her son came to suffer from an enlarged heart.
“They said they don’t know what caused it,” she said. Cardiomegaly has a number of causes, but some of the most common are high blood pressure or coronary artery disease, according to WebMD.
The mother said she is troubled by the unexplainable loss, saying that her son never told her of any serious health issues and that a recent physical had shown no signs of problems. She added that he wasn't taking any medications.
“He never complained about his health and we would talk frequently,” she said. "This is a condition that can lead to death if it’s triggered, but he never showed any symptoms like hypertension. Nothing.”
She described Griffin Gutwa as being “very active” in high school; on the court as a basketball player and also in church serving as a dedicated deacon at the Southview Seventh-day Adventist Church.
Griffin Gutwa's uncle Bernard Gutwa added: "He was a very active boy and a good basketball player. Some of his basketball team players are the ones who are being invited to serve as his pallbearers."
A future lost
The family hopes a crowdfunding site, which so far has raised almost $5,000, will help fund the teen's burial.
"We are trying to arrange for family members to come from Africa to be here for it," Makori said.
But for the family, part of what's most difficult is the future Griffin Gutwa lost.
Bernard Gutwa said his nephew told him in October that he was eyeing Ivy League medical schools and was eager to dedicate himself to treating Kenya's sick and misfortunate.
"He wanted to start a nongovernmental organization to cater to poor people; especially people that were not well," Bernard Gutwa said. "He wanted to be part of that mission."
“Griffin loved everybody from older people to kids,” Makori added. "You could not pass Griffin without him saying, ‘Hi.’”