Nikola and its founder Trevor Milton received grand jury subpoenas from the U.S. Department of Justice in September in connection to allegations of fraud by short-seller Hindenburg, the electric-truck maker said in a regulatory filing late on Monday.
The company also received a grand jury subpoena from the New York County District Attorney's Office in the same month.
The U.S. Securities and Exchange Commission also issued subpoenas to Nikola, its board and eight of its officers and employees in September, the company disclosed in the filing, which was prompted by the short-seller's scathing report earlier that month.
The report had claimed that Milton, who has since resigned as chairman, had made false claims about the company's proprietary technology to form partnerships with large automakers. Nikola publicly rejected all accusations.