The U.S. Attorney for the Northern District of West Virginia said agents tracking down a Mountain State doctor helped the government file charges against a London-based bank.

U.S. Attorney William Ihlenfeld said it started with a health care fraud investigation that led agency to question why the bank – HSBC – didn't notice illegal activity.

The bank forfeited nearly $2 billion, one of the largest settlements in the U.S. justice system.

Ihlenfeld said investigators worked with the IRS and other agencies and determined the doctor was not only "falsely billing Medicare and Medicaid, but he was taking the proceeds from that billing and he was laundering the money. And he was laundering through bank accounts with HSBC."

He said West Virginia investigators determined that HSBC didn't have an adequate anti-money laundering program at the bank.