The security software maker said it had received a grand jury subpoena from the US Attorney’s Office for the Northern District of California, and intends to cooperate fully.

The subpoena, McAfee said, related to its May firing of general counsel Kent Roberts, and his stock options-related activities, and McAfee’s internal and external accounting probes.

In the US, a grand jury is used to decide whether to bring indictments against a person or organization. McAfee did not disclose the full details of the grand jury investigation. Friday’s revelation will do little to calm investor nerves.

The company is one of about 75 US public companies under the scrutiny of the Securities and Exchange Commission.

It is also on the Nasdaq’s steadily growing delisting agenda, having failed to file its most-recent quarterly report on time, while it assesses the extent of its restatements.

In May, McAfee said it had fired Roberts, after discovering an episode of improper options accounting six years ago.

In late July, the company revealed that it has discovered problems with its options accounting, and would probably have to restate previous quarters’ earnings as a result.

The accounting measurement dates for certain stock options dates granted differ from the measurement dates previously used for such awards, CFO Eric Brown said at the time.

The practice of incorrectly accounting for backdated stock options was evidently widespread, though not necessarily always outright fraudulent.

Regulators and law enforcement are aggressively chasing companies and executives they believe to have defrauded investors, with charges already filed against at least three individuals at other companies.