Tesla chief executive Elon Musk, already under scrutiny for his public outbursts, appeared to smoke marijuana during a live interview with comedian Joe Rogan.

The two-hour interview, which aired during Rogan's podcast on Thursday and which is available on YouTube, shows Musk and Rogan talking about technology, samurai swords and other topics, including marijuana. When Rogan pulled out what he described as a joint comprised of tobacco and marijuana, Musk asked, "I mean, it's legal, right?"

"Totally legal," Rogan replied as Musk reached for the joint. Rogan added, "How does it work? Do people get upset at you if you do certain things?" Musk shrugged in response.

Get Breaking News Delivered to Your Inbox

Tesla didn't immediately respond to a request for comment.

The interview was taped in California, where marijuana is legal. Yet the incident could revive questions about whether Musk is the right person to lead Tesla. In recent weeks he has drawn criticism for claiming that a British diver who assisted in the rescue of a youth soccer team from a flooded cave in Thailand is a child molester.

"Elon's actions are making it harder and harder to support Tesla as a company," wrote Gene Munster, a managing partner at Loup Ventures who has been a significant backer of Musk's.

"The use of recreational drugs, legal or not, goes against the unspoken rules of being a public CEO," Munster wrote.

"At the core, we believe he wants to prove his doubters wrong, but many of his actions strengthen the case against him. If he wanted to prove them wrong with actions he would delete Twitter, drop the Unsworth conversation, and not use recreational drugs in a public setting," Munster added.

Musk startled investors on August 7 when he tweeted that he planned to take the company private, only to suddenly reverse those plans weeks later.

That about-face has sparked an investigation by securities regulators reportedly focusing on the veracity of Musk's claim that he had secured funding for the deal. Investors who have bet that Tesla's stock price will fall, or "short sellers," also have filed a lawsuit against Tesla and Musk alleging that the take-private proposal was a ruse aimed at lowering the value of their holdings.

Tesla shares fell more than 6 percent on Friday. The stock has plunged 31 percent since Musk floated the idea of taking the car maker off the public market, lopping billions of dollars off the company's market value.

In a New York Times interview published in August, Musk talked about the toll the stress of running Tesla had taken on him, reportedly shedding tears.

Executive departure

In another sign of trouble for Tesla, the company's chief accounting officer resigned Tuesday after only one month in the role, saying the level of scrutiny on the company had made him reconsider the job.

"Since I joined Tesla on August 6th, the level of public attention placed on the company, as well as the pace within the company, have exceeded my expectations," Tesla's chief accounting officer, Dave Morton, wrote in his resignation letter, according to a regulatory filing. "As a result, this caused me to reconsider my future."

Later Friday afternoon, Musk announced promotions and hyped Tesla's future in a staff letter.

"We are about to have the most amazing quarter in our history, building and delivering more than twice as many cars as we did last quarter," the letter said, in part. "For a while, there will be a lot of fuss and noise in the media. Just ignore them. Results are what matter and we are creating the most mind-blowing growth in the history of the automotive industry."