Inside the troubled past of billionaire Nikola founder Trevor Milton

• Trevor Milton left Nikola after he was accused of lying and exaggerating about its products.
• Insider spoke with 38 people who have worked for Milton or interacted with him.
• Some said he has a long history of bending the truth.

Last summer, Trevor Milton was a newly minted billionaire with a startup that was more valuable than Ford. His company, Nikola, hoped to do for hydrogen-powered semi trucks what Tesla had done for electric sedans and SUVs.

But in September, Hindenburg Research, a financial-research firm that bets against companies it thinks have misbehaved, published a scathing takedown of Milton and Nikola, saying they had made a series of exaggerations and misrepresentations about the company's products. Milton denied the allegations - although Nikola would later admit at least nine of them were true - but it set off a chain reaction that led to him stepping down from the company.

Where Milton had recently drawn comparisons to Tesla CEO Elon Musk, he now looked more like WeWork founder Adam Neumann, another ambitious, charismatic entrepreneur who left his company amid criticism over his behavior.

In August, Insider began talking to people who have worked for Milton or interacted with him, including friends, investors, and former employees.

Some said Milton has a long history of bending the truth that stretches back to the first startups he founded in his 20s. Milton, his critics say, has lied to boost his reputation, misled partners and coworkers about his companies' products, and claimed he and his employees built parts they bought from suppliers.

"As you work closely with him, you begin to see that he struggles to tell the truth about anything," a former coworker told Insider.