Gary Joseph Gravelle, 51, was arrested in New Britain by members of the U.S. Marshals Service Violent Fugitive Task Force and the New Britain Police Department, said the Department of Justice.
Although not charged in Wednesday's incidents that included at least five packages containing white powder being found in four Hartford buildings, including a state office and a federal courthouse, and a bank, officials said he was under investigation.
He was charged with violating the terms of his release.
According to statements made in court, Gravelle is under investigation for sending multiple threatening communications and for mailing multiple letters containing white powder to several federal and state offices, and community organizations.
In 2013, Gravelle was sentenced in Bridgeport federal court five-and-half years in prison, followed by three years of supervised release, for mailing numerous threatening letters. He was released in Nov. 2015, the DOJ said.
On Thursday morning, DOJ officials confirmed police were investigating a sixth incident at a Motel 6 in Southington.
The investigation is continuing. Anyone with pertinent information is asked to call the FBI at 203-777-6311.
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