A Massachusetts man has been arrested for allegedly cyberstalking Katie Miller, the wife of White House Deputy Chief of Staff for Policy Stephen Miller.

John Anthony Proia III, 41, of Waltham, was charged Thursday with cyberstalking a 'former political advisor and prominent member of the Republican Party' who is married to a 'high-level federal government employee,' the FBI announced.

The indictment filed in federal district court in Boston does not name the Millers, but sources confirmed to CBS News that they were the victims. 

'Thank you Todd Blanche, Leah Foley and the Washington Field Office,' Katie Miller wrote on X while sharing a post about the case from Attorney General Todd Blanche.

The indictment comes after Proia allegedly barraged Katie Miller with more than 40 calls and texts between August and September, some of which came late at night. 

Proia was also said to have contacted Katie Miller's mother and father, leaving them a number of disturbing text messages.

In one of those texts to Miller's mother, prosecutors said Proia asked: 'Does it disturb you that such evil as [Stephen Miller] is married to the creature that slithered from your c***?'

In another, he allegedly referred to Katie Miller's father by name and said: 'hope your daughter marrying a Jewish Nazi/white supremacist is working out for you.'

Prosecutors added that Proia often used expletives and a 'menacing tone' in his communications.

He then allegedly employed an internet-based phone system that allowed him to hide his identity and change his phone number.

'Cyberstalking can inflict real fear and harm, and we take these allegations extremely seriously,' US Attorney Leah Foley said in a statement.

'Those who use technology to harass, intimidate or torment others should understand that attempts to anonymize their criminal conduct will not shield them from prosecution,' she continued. 'We will find you and we will hold you accountable.'

Ted E Docks, Special Agent in Charge of FBI's Boston Division, added: 'Terrorizing someone isn't some sick game, it's a crime, which is why the FBI and our partners take it so seriously as we work to protect and serve everyone in our communities.'

But the charges against Proia only came after the Millers complained that the FBI wasn't doing enough to investigate the harassment – leading to two senior counterterrorism agents being demoted from their positions, according to CBS.

Darren Cox, who leads the Washington Field Office, has since issued a statement insisting he was the one who made the decision – and not FBI Director Kash Patel.

Proia's arrest marks at least the second time Katie Miller has asked the FBI to investigate alleged threats or harassment.

Last year, she complained to local and federal law enforcement after local activist Barbara Wien distributed flyers near the Millers' home in Arlington, Virginia, showing Stephen on a 'Wanted' poster for 'crimes against humanity.'

It included the couple's address in Arlington and provided viewers with a QR code, urging them to demand a congressional investigation into his conduct.

The incident prompted the Millers to move into military housing.

But the federal investigation into the matter hit a dead end after a magistrate judge twice rejected a search warrant for Wien's phone.

The state investigation also ended earlier this year, after Arlington and Falls Church Commonwealth Attorney Parisa Dehghani-Tafti said in a lengthy court filing that she reviewed the evidence against Wien and found that 'nothing in the proceeds of the search warrant supports criminal prosecution.'