JOHNSON CITY, Texas — Angela Chao had much to celebrate on the Chinese New Year, dawn of the year of the dragon, a symbol of prosperity so auspicious that mothers timed pregnancies to its arrival.

She was chief executive of her family’s growing global shipping operation and had steered the business through years of disruption. She had a 3-year-old son James, the namesake of her husband Jim Breyer , a billionaire venture capitalist. Chao and Breyer had made some big life changes during the pandemic, moving their primary residences from Manhattan and the Bay Area to the sunny boomtown of Austin, Texas, buying an Italianate mansion downtown and a sprawling ranch just under an hour west.

Chao, 50, had invited seven girlfriends from her days at Harvard Business School to spend the holiday weekend of Feb. 9 at the ranch. It was a gorgeous retreat, with a dozen horse stables, a swimming pool, a putting green, a basketball court and a 10-bedroom guesthouse known as “the inn.” A stone patio offered breathtaking views of the Hill Country, especially at sunset as the light glinted off the small ponds dotting the property.

Chao’s friends flew in Friday evening and spent the next day roaming the ranch’s 900 acres, as Chao showed off the topography, including a mile-long stretch of Miller Creek, crossed by two dams, and the wildlife, including Rio Grande turkeys and exotic Axis and Stika deer, so different from New York City where her friends lived. They had barbecue delivered for dinner and spent the evening catching up. Around 11:30 p.m., Chao left the inn to head back to the main house. Her son was asleep, under the watch of the nanny, and she wanted to be home when he woke up the next morning.

The weekend she died Angela Chao had been celebrating Chinese New Year with friends at her 900-acre ranch outside of Austin, Texas. PHOTO: MARY INHEA KANG FOR THE WALL STREET JOURNAL

The night was chilly and very dark, with no moon, so rather than walk, Chao got in her Tesla Model X SUV for the four-minute trip back to the house.

The account of what happened to Angela Chao that weekend is based on interviews with people close to Chao and her family, county officials who were briefed on what happened or were there, as well as reviews of law-enforcement documents.

Within minutes of saying her goodbyes, she called one of her friends in a panic. While making a three-point turn, she had put the car in reverse instead of drive, she said. It is a mistake she had made before with the Tesla gearshift. The car had zipped backward, tipping over an embankment and into a pond. It was sinking fast. Could they help her?

Over the next several hours, her friends, then the ranch manager and his wife, and then paramedics, and firefighters and sheriff’s deputies rushed around and tried to break the windows, find an escape hatch or any way to get Chao out of the car. Somehow an executive who made her living on the sea was drowning in a stock pond within sight of her home.

Halfway around the world, it was midmorning on Sunday. Jim Breyer was in Dubai on the way to a conference center for the United Arab Emirates World Government Summit, where he would be speaking on a panel about artificial intelligence and medicine, his latest professional passion. He was in a car with a colleague when the phone rang. It was one of his wife’s girlfriends. There had been a tragic accident, she said.

In the background, Breyer could hear the buzz of activity. His wife’s friend said there were deputies, paramedics and firefighters trying to revive Chao, but her car had been underwater for a long time. Breyer heard someone ask to speak with him, the voice on the other end of his wife’s friend’s phone.

The man identified himself as being with EMS. He asked who he was speaking to.

“What’s the relationship to the deceased?” the man asked.

“It’s Jim Breyer,” he said. “I’m her husband.”

One minute to escape

A driver has about one minute to get out of a car sinking into water. When vehicles were made with more manual mechanics, a driver could crank down the window to get out, though it would still require a clarity of mind often elusive in an emergency. In newer cars, like the Tesla Model X vehicle, the driver might have seconds to push the button to roll the window down before the water level rises too high. After that, the only mode of exit would be by breaking it, say auto safety experts.

That is terribly difficult underwater and can be even more so when trying to bash through tempered glass or sturdier laminated glass, which most car companies use today. Those are the two types of glass that Tesla may have used in its 2020 Model X, according to company documents. Laminated glass, in particular, is lauded for its safety qualities, such as preventing a driver from being ejected during a crash; however it is nearly impossible to break underwater, according to testing done by the American Automobile Association.

Tesla didn’t respond to requests for comment.

Every year, about 400 people die in motor-vehicle submersions in North America, according to researchers who have studied these incidents. There are no requirements to protect occupants in vehicles submerged in water, according to federal safety regulators.

Though she was one of the world’s most powerful women, Angela Chao was little-known outside the world of shipping. She was the youngest of six sisters, four of whom, herself included, attended Harvard Business School. Chao majored in economics at Harvard, graduating magna cum laude in just three years. The school’s Ruth Mulan Chu Chao Center for executive education is named after her late mother, who, along with Angela’s 96-year-old father James S.C. Chao, co-founded the Foremost Group shipping company, which carries more than 20 million tons of dry goods a year for companies like Bunge and Cargill.

Chao’s older sister Elaine was U.S. Secretary of Labor in the Bush administration and U.S. Secretary of Transportation in the Trump administration. Elaine Chao is married to Senate Minority Leader Mitch McConnell (R., Ky.).

The Chao family’s closely held New York-based business is valued at $1.3 billion. Angela Chao had twice married billionaires. In 2009, she became the fourth wife of Bruce Wasserstein, the head of Lazard, whose role advising Kohlberg Kravis Roberts in the 1988 takeover battle of RJR Nabisco kicked off a new era in corporate mergers and acquisitions. When Wasserstein died of a heart attack nine months after their marriage, Chao retained his apartment at 927 Fifth Avenue, one of the most exclusive co-ops on the Upper East Side, due east of Central Park’s model-boat pond.

In 2012, Chao married Jim Breyer. They had met the prior year when seated at the same table at a Metropolitan Museum of Art gala. Breyer was an early investor in Facebook , and has become one of the most successful Silicon Valley venture capitalists. He also sits on the board of private-equity giant Blackstone .

She took pride in her 21-year prepandemic streak of attending every opening night at the Metropolitan Opera House, where she was an advisory director on the board. She was a member of the Council on Foreign Relations and, though she was born in the U.S., had become near-fluent in Mandarin. She and her husband attended the World Economic Forum in Davos in mid-January.

Rescue attempts

When her car went underwater, all the power and status in the world were irrelevant. The local officials trying to save her didn’t know who she was. All they knew was that it was dark and the water was black and cold. They couldn’t even be sure that the submerged structure they were standing on was her metallic dark blue Model X.

After Chao made her pleading call, her friends came outside. One jumped in the pond. Amid the commotion, the property’s ranch manager came outside with his wife. 911 was called. Some responders arrived.

One emergency unit for Blanco County, where Johnson City is located, got there at 12:28 a.m., about 24 minutes after getting a call, according to a fire department incident report. The terrain and accessibility were such that some first responders decided to get out of their vehicles and walk to the exact location. One responder described the Tesla as completely submerged, with some deputies standing on it as they tried to get in to rescue Chao.

The responders set up lighting. Rescue workers needed a dive team, but none was available, according to the incident report. More emergency workers arrived on the scene as the deputies on top of the car requested tools to break the window. An emergency services worker and firefighter entered the water with rescue tools.

A tow truck came but didn’t have a cable long enough to reach the vehicle. Some on the scene didn’t expect the vehicle to be so far out in the pond, but responders eventually retrieved a longer cable. At least one tow driver, not used to towing an electric vehicle out of water, was afraid of being electrocuted, said a person who was at the scene.

It turns out that when submerged in water, an electric vehicle is designed to not pose a shock risk because the high-voltage battery is isolated from the frame of the car, according to the National Fire Protection Association, a nonprofit organization that develops fire-safety codes and standards.

After the car was towed from the water, the doors of the vehicle were opened and hundreds of gallons of water rushed out. Chao was unresponsive, according to Ben Oakley, emergency services chief of Blanco County. She was pulled from the vehicle and attempts were made to resuscitate her, but to no avail.

Angela Chao and her husband moved to Austin during the pandemic. They bought a mansion in downtown and a 900-acre ranch to escape city life. PHOTO: MARY INHEA KANG FOR THE WALL STREET JOURNAL

Oakley said Chao was deceased at the scene and not taken to a hospital. No autopsy was performed. More than two hours after arriving, the emergency vehicles cleared out. The car was towed to a law-enforcement facility and returned to the property shortly thereafter.

The move to Texas

The couple had decided to move to Austin after dinner there in the fall of 2019 with some longtime friends, Susan and Michael Dell , founder of his namesake computer company. The Dells told them lovingly, but firmly, that they were spending too much time going back and forth between New York and San Francisco. Back at their hotel that night, the couple decided to go for it, reckoning, too, that they had a baby on the way and it would be good for him to grow up in one place. Like several other billionaires, they arrived in Austin at the height of the pandemic.

Their ranch’s rural setting is what locals say gives the area its character. They cautiously watch the signs of growth: Johnson City, population 1,700, went from having zero stop lights to two. Residents expressed concern about the potential for more traffic being routed through town due to a controversial road project. Some locals said they had never laid eyes on Chao or Breyer or even heard that the billionaire couple had a home in Blanco County.

The local EMS station has one ambulance to cover 7,000 people spread out over 200 square miles. Properties more than two miles away from the station are generally given the weakest insurance safety rating of 10 based on how quickly help can arrive. The ranch is twelve miles from the station. New York, Austin and other major cities have a rating of one, by contrast.

“There are quite a few wealthy people that have these ranches, which are just big ranches with the nice homes,” said Kenneth Welch, a retired engineer who has lived in Blanco County for 17 years. “They’re gated and you can’t just drive in.”

Johnson City , Texas. PHOTO: MARY INHEA KANG FOR THE WALL STREET JOURNAL

Ten days after she died, there was a short report inside the weekly paper, the Blanco County News. The front page was dominated by a student’s blue-ribbon welding project in a Future Farmers of America competition. The other pages were filled with updates on livestock shows and real-estate ads, offering houses in the $300,000 range and ranches in the $5 million range and not much in between.

The Sheriff’s Office has denied requests for information, citing its ongoing investigation. “Although the preliminary investigation indicated that this was an unfortunate accident, the Sheriff’s Office is still investigating this accident as a criminal matter,” the Blanco County public information officer said in a Feb. 29 letter to the Texas attorney general to explain why public-information requests should be denied. The officer said, in an email Friday, that the investigation hasn’t been completed.

Chao’s death spawned a slew of conspiracy theories far from Johnson City, which has angered and frustrated her close-knit family. Strangers spouted off on Reddit forums and on the platform X, formerly known as Twitter, theorizing about foul play and her family’s ties to the Chinese.

Hedge-fund manager Kyle Bass, who owns multiple Texas ranches, tweeted on March 1: “Does the Blanco County Sheriff have the technical capacity to investigate the Tesla Logs to determine if the car was tampered with or even hacked? This case continues to become more and more suspicious.”

In a recent segment on Fox Business, anchor Maria Bartiromo described Chao as a “sweet woman” she had just seen in Davos. She talked about the family’s economic and political ties to China and about the possibility that Chao was murdered, in a discussion with Gordon G. Chang, a lawyer and critic of the Chinese regime.

“We can’t really put anything beyond the Chinese right now,” Chang said. “At the very least this should be considered a murder investigation.”

It is nonsense to say that doing business in China makes an American executive a Chinese Communist Party sympathizer, said Norman Chen, director of the Asian American Foundation, founded three years ago in response to a rise in anti-Asian hate. He said the speculation also besmirches the memory of a woman who fought against xenophobia.

Mitch McConnell’s decision

Angela Chao’s father, James Chao, had business dealings with China for decades. Breyer invested in DiDi, a Beijing-based ride-for-hire company, and ​​Angela was chair of the U.S. Risk and Management Committee of Bank of China U.S.A., a unit of one of China’s biggest commercial banks.

When McConnell said he would step down as Senate minority leader last month, he began his announcement with a discussion of his sister-in-law’s death: “This has been a particularly difficult time for my family. We tragically lost Elaine’s younger sister Angela just a few weeks ago. ” The death was a factor in the timing of his decision to step down, a person familiar with the matter said.

No one in the family blames Tesla, according to a person familiar with the situation. Breyer and his wife had three Teslas and loved them, and often spoke about how electric vehicles were good for the planet. Breyer considers himself a friend of Elon Musk ’s.

In 2016, the National Highway Traffic Safety Administration denied a petition to require carmakers to equip every vehicle with a glass-breaking tool, saying the effectiveness of such a tool isn’t known.

Many drivers mistakenly think that they should try to open their door if their car becomes immersed in water, said Gordon Giesbrecht, a senior scholar at University of Manitoba who studies vehicle-submersion deaths. Due to the pressure of the water, it would be nearly impossible to open a submerged car door.

Corrections & Amplifications undefined Gordon G. Chang, a lawyer and critic of the Chinese regime, raised the possibility of Chinese involvement in the death of shipping executive Angela Chao. An earlier version of this article incorrectly attributed the comment to Gordon H. Chang, a Stanford historian. (Corrected on March 9)

-Ryan Felton, Rebecca Elliott, Jim Oberman, Elisa Cho and Costas Paris contributed to this article.

Write to Valerie Bauerlein at Valerie.Bauerlein@wsj.com , Tawnell D. Hobbs at tawnell.hobbs@wsj.com , Cara Lombardo at cara.lombardo@wsj.com and Elizabeth Findell at elizabeth.findell@wsj.com