'I'm going to kill you!' - Pennsylvania man charged with threatening to kill January 6 investigator

• Robert Vargo was arrested for threatening the chair of the committee investigating the US Capitol attack.
• Vargo also threatened to kill US President Joe Biden.
• Vargo escaped from jail in Pennsylvania.

A US grand jury has indicted a jailed Pennsylvania man for threatening to kill the chair of the congressional committee investigating the January 2021 assault on the US Capitol, prosecutors said on Wednesday.

Robert Vargo, 25, of Berwick, Pennsylvania, also threatened to kill the committee chair's family and US President Joe Biden, prosecutors said.

He was charged with threatening the president of the United States, threat by interstate communications, and influencing a federal official by threat, the US Attorney's office for the Middle District of Pennsylvania said in a statement.

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Reuters could not immediately identify the lawyer representing Vargo in order to seek a comment in his defence.

Vargo, who once escaped from the Pennsylvania jail where he is being held, could face up to 25 years in prison if convicted of the federal charges.

Prosecutors allege Vargo sent a threatening letter and white powder to the congressional office of US Representative Bennie Thompson, chair of the committee that is investigating the 6 January 2021 attack on the Capitol.

The letter, which referenced the congressional probe and anthrax, also threatened US District Court Judge Robert Mariani, according to prosecutors.

"I'm going to kill you! I will make you feel the rest of our pain & suffering," the letter to Thompson said. "There is nowhere or nobody who can keep you from me. I am going to kill you & those you love."

The letter also says: "You & Joe Biden soon will face death for the wrongs you've done to US."

US Capitol Police who investigated the threat found the white powder to be harmless.

Vargo sent the letter from the Luzerne County Correctional Facility, prosecutors said.

Vargo had escaped from the Pennsylvania jail in July and was caught several days later in South Carolina, according to media reports at the time that cited Luzerne County District Attorney Sam Sanguedolce.