A federal grand jury on Thursday indicted Jack Teixeira, a Massachusetts Air National Guard member who posted dozens of secret intelligence reports and other sensitive documents on a social media server, on six counts of retaining and transmitting classified national defense information.

The filing of criminal charges in Boston federal court against Teixeira, 21, comes about two months after FBI agents arrested him at his home in North Dighton, Massachusetts, and paves the way for a trial stemming from one of the most damaging national security leaks in recent history. If convicted, he could face up to 60 years in prison.

The evidence presented in the 10-page indictment represents a distillation of the immense trove of secrets Teixeira is accused of taking from computers at an intelligence unit at the Cape Cod air base — and sharing with online friends he was hoping to impress in chat groups on Discord, a social media platform popular with gamers. But it was not immediately clear how many of the vaguely described incidents that underlie the charges had been previously disclosed and which ones were being made public for the first time.