Mom-of-two Stefanie Smith's cause of death is revealed after she died on American Airlines flight returning from vacation with her boyfriend in the Dominican Republic

An Indiana mother-of-two who mysteriously died on her flight home from the Dominican Republic died of natural causes, her family has revealed.

Stefanie Smith, 41, died from a carotid artery dissection in her neck, her brother Chris Volz told ABC News on Wednesday. He described the incident as a 'truly a tragic medical event' and said the autopsy results do not suggest any foul play.

Smith and her boyfriend had joined close friends Maria Yannotti, 36, and Clay Sharpe, 43, for a five-night stay at the all-inclusive Iberostar Grand Bavaro in Punta Cana, Dominican Republic.

But the romantic couples' getaway turned to tragedy minutes into her return flight when she started convulsing and was declared dead after the American Airlines plane diverted to the Turks and Caicos Islands.

Volz previously told DailyMail.com he was not aware of his sister having any preexisting health conditions. Yannotti also claimed Smith was picture of health throughout their vacation, using the hotel gym and going for runs along the beach.

Stefanie Smith, 41, was just minutes into the American Airlines flight home from the Dominican Republic when she became fatally ill from an unknown cause on February 28 

Smith is pictured with her two children. The late mom's cause of death has now been revealed by her brother 

Her brother Chris Volz, pictured with Stefanie Smith, has revealed that she died from a carotid artery dissection in her neck

Maria Yannotti, who was on holiday with Smith, said she was picture of health throughout their vacation, using the hotel gym and going for runs along the beach

Smith and her boyfriend had joined close friends Maria Yannotti, 36, and Clay Sharpe, 43, for a five-night stay at the all-inclusive Iberostar Grand Bavaro in Punta Cana, Dominican Republic 

'Stefanie was a ball of energy and personality. She was so much fun to be around. She could make anyone smile,' Yannotti told DailyMail.com last week.

'What's happened is just devastating for everyone. We don't know if it was just a freak accident or something more. Until we get the autopsy back it's just a complete mystery.'

IUPUI graduate Smith and her partner, who has asked not to be named, flew to Punta Cana on February 23, meeting up with Sharpe and Yannotti during their connection in Miami.

The couples booked separate rooms at the adults-only Grand Bavaro, a luxurious beachfront retreat boasting three pools, a golf course, private butlers and personal trainers.

The luxe all-inclusive has five fine dining restaurants stocked with high-end liquor brands and house wines from Spain, Chile, Italy and the US, as well as a buffet and '24-hour gourmet station'.

Punta Cana's sun-drenched resorts came under the microscope in 2019 after a spate of American tourists died in unexplained circumstances.

An FBI investigation later revealed there was nothing sinister about the deaths, however, which were all unconnected and put down to natural causes.

'We didn't leave the resort the whole time, there was no need to,' added Yannotti, who has been several times before to the Grand Bavaro, where rooms cost upwards of $690 per night.

Smith is pictured with friend Maria Yannotti during their vacation in the Dominican Republic. Yannotti told DailyMail.com that they enjoyed mojitos and steaks on the trip 

Maria Yannotti previously shared a photo from the trip with DailyMail.com. The couples had stayed at the Grand Bavaro, where rooms cost upwards of $690 per night

Smith, 41, and her boyfriend (right)  joined close friends Maria Yannotti, 36, (third from left) and Clay Sharpe, 43, (left) for a five-night stay at the all-inclusive Iberostar Grand Bavaro in Punta Cana, Dominican Republic

The Cheshire Hall Medical Centre in the Turks and Caicos where Smith was pronounced dead 

The two women drank socially but not to excess. Yannotti dismissed any suggestion that her fitness-loving friend would take illegal drugs.

'The level of drinking never went beyond what I would call a nice little buzz. We pretty much had the same drinks. We enjoyed the strawberry mojitos made with Malibu rum,' she said.

The four typically ate a mix of American and international dishes in the hotel's buffet for lunch and breakfast, soaking up the sun or hitting the beach throughout the day.

'It's five-star, very secure. I always felt very safe. The food was great. Everything was very clean, very upkept,' Yannotti recalled.

Stefanie Smith worked as an x-ray technician at OrthoIndy Hospital in Indianapolis 

On the final day of their stay, they left the beach at around 5pm, went to their rooms, showered, and met up at El Galeon, a swish on-site surf and turf restaurant.

Yannotti and Smith chose the same entrée, ribeye steak, which they paired with a bottle of Moscato wine which was opened and poured in front of them.

'It was exquisite cuisine,' Yannotti recalled. None of the group complained about feeling unwell at any stage throughout the trip, and that night was no different, she added.

Afterwards, Smith and her boyfriend spent an hour or so in Yannotti and Sharpe's room, reflecting on their 'amazing' vacation, vowing to do it again, before they all said their goodbyes.

Yannotti was flying home to Baxley, Georgia on a different flight leaving several hours after Smith was due to take off from Punta Cana International Airport, headed to Charlotte.

The pair texted back and forth, discussing how long the customs line would likely take, before Smith sent her final, haunting message at 4.55pm eastern.

'Remind me to call you when we land in Charlotte, to tell you a funny story,' she wrote, using the plane's in-flight Wi-Fi.

At 6.12pm local time air traffic controllers in the Turks and Caicos asked first responders to meet American Airlines Flight 2790, which was diverting to Providenciales International Airport because of a medical emergency.

Smith was rushed to the Cheshire Hall Medical Centre where she was declared dead.

'We were sitting in Miami on our layover. The boyfriend called and said that he had something to tell us. He said Stefanie had died. She's gone and he wasn't sure what happened,' Yannotti said.

'He said he looked at her and her head was tilted back into her seat. Her eyes were rolled into the back of her head and he thought she was making fun of him at first.

'Then she started convulsing and that's when he called for help and they performed CPR and the pilot decided to make the call to land.

'It floored me. I was in complete shock. I had been texting her just minutes before we received that phone call.'

Stefanie Smith was mother to heartbroken teens Coen, 18, and Macee, 16

Stefanie Smith had gone through a divorce recently from husband Eric Smith, 44, the father of their two children

Smith, who worked at OrthoIndy Hospital in Indianapolis, had gone through a divorce recently from husband Eric Smith, 44 - the father of their two children, Coen, 18, and Macee, 16.

She met her current partner about a year to a year and a half ago, Yannotti told DailyMail.com.

'Stefanie had just built a brand-new beautiful house. She had a great job, two great kids. She had absolutely everything going for her,' she said.

'We all say life is short, live every day like it's your last, that sort of thing. But you don't truly appreciate what that means until something happens to someone you love.'

A GoFundMe appeal to raise money for Smith's teenaged children has already received more than $94,000 in donations, with passengers from Smith's flight among those who have contributed.

'I didn't know Stefanie but I was in the row in front of her,' wrote Erika Remillard-Hagen. 'When I was 41 my own two children were the same age hers are. My heart breaks for her family.'