A South End man was arrested today on charges he tried to defraud the One Fund Boston charity out of $2.195 million by claiming his aunt was injured during the Boston Marathon terror bombing, when she had been dead for a decade, Attorney General Martha Coakley’s office said today.

Branden Mattier’s booking photo
Mass. Attorney General

Branden Mattier was arrested by an undercover Massachusetts State Police trooper at his home today when the 22-year-old accepted a simulated check that was, on paper at least, worth millions of dollars, Coakley said in a statement.

Mattier is expected to be arraigned in Boston Municipal Court on Wednesday, according to Coakley’s office. Mattier is charged with attempted larceny over $250 and identity theft, according to Coakley’s office.

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“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,’’ Coakley said of Mattier in a statement. “We commend the One Fund for uncovering this and for referring it to our office for further investigation.”

According to prosecutors, managers at the One Fund Boston became suspicious about Mattier’s claim and asked the attorney general’s office to investigate.

Camille Biros, deputy administrator of One Fund, said today that Mattier’s application stood out from the hundreds of others submitted to the charity created to help the victims of the Marathon bombings.

“It just seemed a little unusual,” she said today.

The paperwork Mattier submitted to support his claim was so distinctly different from other claims, administrators promptly forwarded the claim to investigators, Biros said.

Mattier attended a town meeting held at the Boston Public Library on May 7 and asked fund managers if his aunt would qualify for aid if she underwent amputations in the future, prosecutors said.

In June, Mattier allegedly sent the One Fund Boston a letter written by the chief of trauma services at Boston Medical Center confirming that Mattier’s aunt had undergone a double amputation.

The letter from the BMC was a forgery, prosecutors said. Mattier’s aunt, identified by prosecutors as Oneiva Bradley, was never treated at Boston Medical after the terror bombings that killed three and wounded more than 200, prosecutors said.

In fact, prosecutors said, Bradley died more than 10 years ago.