Uber is now facing a criminal investigation, report says

Uber's problems just went from really, really, bad to worse.

As if its months-long PR nightmare wasn't bad enough, the company is reportedly now the subject of a criminal investigation.

The U.S. Department of Justice is investigating the company for its use of a controversial software program known as "Greyball," Reuters reported Thursday.

Greyball, first reported by The New York Times, was a tool developed internally at Uber used to thwart regulators and local officials in cities where they faced regulatory hurdles. Uber employees would use the software to identify government offices and employees, and load fake versions of the app as a means of evading law enforcement and other crackdowns.

The investigation "is still in its early stages," according to the report, which cited two unnamed sources. From the report:

Uber received a subpoena from a Northern California grand jury seeking documents concerning how the software tool functioned and where it was deployed, one person familiar with the request said. That indicates a criminal investigation is underway. The second source confirmed that was the case.

It's not yet clear if Uber will be charged or what the charges may be. Officials in Portland, Oregon, previously came out against the company for its use of Greyball after media reports brought the software to light.

Uber's CTO later said the company would "review" the technology and that it would stop using Greyball as a way to target regulators.

An Uber spokesperson didn't immediately respond to a request for comment.