A Boston man has been arrested for submitting a $2.2 million false claim to The One Fund Boston, the charitable fund to help victims of the Boston Marathon bombing.

Branden Mattier, 22, of the city's South End, allegedly filed the false claim on behalf of his aunt, who he said was a double amputee as a result of the Patriots' Day attack. In fact, according to prosecutors, the aunt died more than 10 years ago.

Mattier has been charged with attempted larceny over $250 and identity theft.

“Because every dollar was allocated to victims, he sought to take these funds away from real victims of the Marathon attack and from the thousands of people who had so generously given to help those who truly need it," state Attorney General Martha Coakley said in a press release detailing the charges.

In June, the fund referred the issue to Coakley's office after it suspected Mattier's claim, filed on behalf of his aunt, Onevia Bradley, was false. The press release details:

The AG’s investigation revealed that on May 7, Mattier attended a Town Hall meeting at the Boston Public Library on behalf of his supposedly injured aunt, and followed-up on May 29 by sending an email to The One Fund asking if his aunt could make a claim as a double amputee if the amputation was expected to be performed in the future. In June, The One Fund received Mattier’s claim form along with a letter allegedly from the chief of trauma services at the Boston Medical Center affirming his aunt as a double amputee. The letter was dated May 2, a full 27 days before Mattier’s email.

The BMC letter was forged, Coakley's office found in its investigation. Prosecutors then discovered "Bradley had actually died more than 10 years earlier."

Mattier was arrested at his home Tuesday, Coakley's office said, when an undercover state trooper gave him a simulated check for $2.195 million.

Update at 5:45 p.m.: Speaking to our Newscast Unit, Coakley described the arrest in more detail:

Today a State Police trooper dressed in a FedEx uniform approached him, got his identification, told him he had a check for $2.195 million. He signed the receipt for that check and he was placed under arrest.

Coakley added that Mattier's case was the only instance of potential One Fund fraud that her office investigated.