The Department of Justice has launched a criminal investigation into Uber’s use of a secret software that was used to evade authorities in places where its ride-hailing service was banned or restricted, according to a person familiar with the government’s probe.

The investigation is in its early stages, but deepens the crisis for the embattled company and its chief executive and founder Travis Kalanick, who has faced a barrage of negative press this year in the wake of high-profile sexual harassment complaints, a slew of high-level executive departures, and a consequential trade secrets lawsuit from Google’s parent company.

The federal criminal probe, first reported by Reuters, focuses on software developed by Uber called “Greyball.” The program helped the company evade officials in cities where Uber was not yet approved. The software identified and blocked rides to transportation regulators who were posing as Uber customers to prove that the company was operating illegally.

Uber declined to comment on the criminal investigation. The Department of Justice declined to comment, citing its practice of not confirming or denying possible investigations.

In a letter last week to Portland authorities, who had requested information about the program as part of a civil probe, Uber said greyballing refers to the practice of showing some customers a different version of the app than most customers see. Uber’s attorneys said the program was used “exceedingly sparingly” in Portland, and that the company had not used it since April 2015, when Portland adopted preliminary rules allowing Uber to operate.

Uber, which is valued privately by investors at close to $70 billion, has a reputation among Silicon Valley companies for a hard-charging workplace culture that is driven by Kalanick himself. The 40-year-old is known as a quick-tempered and combative manager who aims to win-at-all costs and inspires fierce loyalty in his inner circle.