Controversial tweets put electric car maker under the spotlight again

The US Department of Justice (DOJ) has opened a second investigation into Tesla, centred around Elon Musk's claims on Twitter funding was secured to take the company private.

Two sources, speaking on the condition of anonymity, have told Bloomberg the DOJ is investigating statements made by Tesla and its CEO.

In a statement, Tesla told the service: "Last month, following Elon’s announcement that he was considering taking the company private, Tesla received a voluntary request for documents from the DOJ and has been cooperative in responding to it.

"We have not received a subpoena, a request for testimony, or any other formal process."

Musk claimed on Twitter on August 8: "Am considering taking Tesla private at $420. Funding secured." By August 25 Tesla announced it had shelved all plans to delist, with Musk stating there was "no proven path for most retail investors to own shares if we were private".

In between those two dates, Musk admitted he only received positive indications from Saudi Arabia's sovereign wealth fund. The Securities and Exchange Commission (SEC) also began a civil investigation into the matter, and two class action lawsuits were launched.

A probe by the justice department could take months to complete, and could result in no charges being laid. One source said it's possible the DOJ could widen its investigation into financial health statements made by the company, as well as the circumstances around the departure of its chief financial officer only one month after he began his role.

Following the Musk's tweet about going private on August 8, the company's share price jumped up to almost US$380 ($521). At the time of writing it is trading at just shy of US$300 ($411).

Tesla's stock market value has taken multiple hits recently, including when Musk smoked marijuana during an interview with The Joe Rogan Experience podcast.

It also dropped after Vernon Unsworth, a diver in the team that rescued a youth soccer team and its coach from a Thai cave, sued the Tesla CEO over repeated comments he made on Twitter claiming Unsworth was a "pedo". Unsworth had earlier disparaged Musk's home-made submarine, designed to aid with the team's rescue.