A federal grand jury has indicted a master sergeant in the Massachusetts National Guard on charges of child pornography in another strike against the Cape base.

Nicholas Wells, 43, who is stationed at Otis Air National Guard Base in Sandwich as part of the 102 Security Forces, was arrested last month on child pornography charges. At an initial appearance in federal court in Boston, Wells consented to voluntary detention.

On Thursday, those charges were bolstered when a federal grand jury delivered an indictment on a count each of possession and distribution of child pornography — with each count carrying a maximum of 20 years in prison.

The next hearing in the case has not yet been scheduled, according to court records.

The U.S. Attorney’s office in Boston said that investigators found more than 300 images and 100 videos of child pornography on Wells’ personal devices, with evidence that he helped to distribute at least 70 videos to others. Some of the child pornography depicts infants.

Wells allegedly wrote at length to an undercover federal agent about his sexual desire for little girls and, even more shockingly, even claimed to have sexually assaulted two young victims, according to an affidavit filed by Special Agent Derek Black to support the charges.

When the FBI executed a search warrant on March 5, Wells allegedly admitted to the allegations when he agreed to speak with agents in a recorded interview.

“WELLS further admitted that he watches videos depicting child pornography and his preference is videos (and photos) that involve underage girls,” the affidavit states.

The Massachusetts National Guard told the Herald that they removed Wells from his position the same day the FBI executed the search warrant. Wells, who joined the Guard in 1998, is barred from Otis, stripped of his security clearance and was scheduled to be separated from the organization on the first of this month.

“The charges against Nicholas Wells are very serious,” a state National Guard spokesperson told the Herald following Wells’ initial arrest. “Criminal activity is not compatible with our values as an organization and will not be tolerated in our ranks.”

This is the same base where Guard tech support member responsible for “one of the most significant leaks of classified documents and information in United States history” was stationed. Jack Teixeira was sentenced this week to 15 years in federal prison.