A cause of death has been identified in the case of the 33-year-old tech founder who went to Silicon Valley on business and was found dead in her car a week later

• A cause of death has been identified in the case of Erin Valenti, a Utah startup founder who went to Silicon Valley on business and was found dead in her rental car a week later last October.
• The autopsy report, which Business Insider has reviewed, determined her death was due to natural causes following an "acute manic episode."
• Last year, Business Insider told the story of Erin Valenti's rise as an entrepreneur and untimely death, based on interviews with almost two dozen friends, family members, current and former colleagues, and the police. You can read our report in full here.
• Visit Business Insider's homepage for more stories.

An autopsy has provided new details on what killed a young female tech founder whose body was found in the back seat of her rental car last year, according to the San Jose medical examiner's office.

Erin Valenti of Salt Lake City was reported missing on October 7, after she missed a flight home from San Jose, California. Her family became worried when on phone calls with Valenti, she became confused and rambling on the drive to the airport.

Five days later, she was found dead with no obvious signs of physical harm.

The autopsy, which Business Insider has reviewed, ruled her manner of death natural and said the cause was "sudden death in the setting of an acute manic episode," though it did not explain what killed the 33-year-old tech founder.

Valenti had gone to Orange County for a professional-development workshop and then flew to the Bay Area to visit former colleagues and friends. She was the chief executive of Tinker Ventures, a web-development shop that builds software for other companies, using a remote staff of engineers in Pakistan. The business was profitable, according to close friends.

Speaking to Business Insider for a profile last fall, friends and former colleagues described her as a dogged entrepreneur who showed a "complete refusal to fail." As chief executive, she was responsible for finding new customers and keeping them, a relentless task for a business that worked on contract, not subscriptions.

The founder seemed ready for a change in the last year of her life. She would call friends on car rides to discuss ideas for a new business venture, or gather them at home to brainstorm over a bottle of wine.

The trip to California included a three-day workshop designed for leaders. One participant likened it to a Tony Robbins seminar for business owners. Her mother, Agnes Valenti, remembers her daughter talking excitedly on the phone about going home and starting something new.

She did not return to see it through.

On October 7, Valenti had just left a friend for the airport when she made a series of strange phone calls to family members. They said she talked fast and erratically, and she wasn't making much sense. She told her mother, "It's all a game, it's a thought experiment, we're in the Matrix."

Her husband, Harrison Weinstein, and her mother took turns talking to her on the phone until almost midnight local time. Then their calls went to voicemail.

New details on her cause of death

A friend in a volunteer search party found Valenti's body in her rental car on a quiet residential street, where the gray Nissan Murrano had been parked for five days. An investigation by San Jose police found no evidence of foul play, authorities said. Blood tests were negative for common prescription drugs and other substances.

"Sudden death has a medical definition," said Sally Aiken, a medical examiner and vice president of the National Association of Medical Examiners. She described it as an unexpected death that happens within an hour of onset and has a natural cause.

Valenti had a previous diagnosis for a thyroid condition that was treated with medication. The autopsy report noted that her condition could have contributed to her death, however, blood samples were not satisfactory for an analysis.

The autopsy report did, however, give new details around her mental state.

A police review of Valenti's electronic communications in the days before her scheduled return confirmed the family's account that she had showed symptoms of a "manic episode," according to the San Jose medical examiner's office.

Authorities also said a review of her medical records "suggest that the etiology of her final manic episode was related to an emerging, previously undiagnosed psychiatric disorder." The family told Business Insider last year that she had no diagnosis of a mental-health disorder.

A manic episode is not a disorder on its own, though it is the principal symptom of bipolar disorder, said Dr. Po Wang, a psychiatrist who runs a clinic for the study and treatment of individuals with bipolar disorder at Stanford University.

One risk of having a manic episode, an event that's characterized by feelings of euphoria, racing thoughts, and feelings of connectedness, is that it's typically followed by a period of depression or irritability, Wang said. The contrast from the high to low feels more dramatic to a person suffering from bipolar disorder. His research and other studies suggest that suicide attempts are common.

Suicide is not the leading cause of death in people with a diagnosis, however.

There is mounting evidence that suggests people with bipolar disorder have higher rates of death from natural causes, like heart disease or a stroke, at an earlier age. A review of studies involving more than 331,000 patients found that "having bipolar disorder is similar to being a smoker in terms of increasing a person's risk of early death," wrote the paper's author, Dr. Wayne Katon, of University of Washington, in a 2009 press release.

There's a number of variables that could be responsible for the higher rates of mortality. People with a diagnosis may be less likely to get medical care or take care of their health, according to the published report. The disorder is also frequently undiagnosed, which leaves many more suffering in silence. A large population study from Stanford University in 2013 found that people with bipolar disorder who knew they had a physical illness, such as heart disease, had death rates similar to people who were not bipolar. The research suggests a diagnosis is part of the antidote to premature death.

Still looking for answers

Erin Valenti's family told Business Insider last year that her behavior in those final calls was "extremely out of character."

They remember her as a tenacious child. She and a friend wrote a newsletter that called out neighbors for smoking and documented all the litter they found. In middle school, she built a database for a scuba diving school as homework and started charging the business to maintain it. She created databases for cash through her years at Georgetown University, where her mother said she would have graduated with a 4.0 if not for a A- in Mandarin. Valenti disputed the grade.

At 18, she met her husband, Harrison Weinstein, at a white clapboard hotel in Quebec, where her family skiied. The couple enjoyed Utah's ample outdoor pursuits like hiking and river-tubing.

Her mother, Agnes, said she had been told that the autopsy might be inconclusive because her daughter's body was found presumably days after her death.

"We may never find an answer," Agnes told Business Insider last year.

Her family established a scholarship fund at the University of Utah to honor Valenti's memory, with a goal of supporting female students who share a passion for entrepreneurship. It has raised more than $100,000 to date.

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