Tesla is being investigated by the U.S. Department of Justice over claims that its electric cars can drive themselves, according to Reuters.

Although news of the criminal investigation has only just come to light, three people familiar with the case told Reuters that the DOJ launched the probe last year in the wake of a series of crashes involving Teslas in which the Autopilot drivers assistance system had been activated.

The revelation comes as the automaker prepares to roll out an improved version of its Full Self-Driving (FSD) software to all Tesla owners who want it. Previously, though many owners had paid for FSD, only a select number of drivers were able to run the Beta software. Speaking about the upcoming software release CEO Elon Musk said the upgraded FSD would let Tesla owners travel to work or the grocery store “without you touching the wheel.”

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This isn’t the first investigation into Tesla’s autonomous technologies, but the same report suggests it could be the most serious yet. Although Tesla is already under scrutiny in California by regulators considering whether the company’s claims about Autopilot gave owners an inflated sense of their cars’ autonomous abilities, the DOJ inquiry could potentially lead to criminal charges against the company or its individual executives. Sources familiar with the investigation said that prosecutors are looking into whether Tesla’s claims about its driver assistance systems misled consumers, investors, and regulators.

Tesla is likely to strongly refute any charges and point to disclaimers on its website stating that its autonomous tech features do not make the vehicle fully autonomous and that drivers activating its basic Autopilot system (essentially an adaptive cruise control) need to keep their hands on the wheel.

And even after making the claim on an earnings call earlier this week that Tesla”s “Full Self-Driving” system would let drivers travel without touching the wheel, Musk then qualified the statement by saying he wasn’t suggesting that the car was ready to drive without anyone behind the wheel.

We’ve asked Tesla to comment on this story and will update this post if we hear back.