DALLAS (AP) — Years after Jacques Roy started filing paperwork that would have made his practice the busiest Medicare provider in the U.S., authorities say they’ve found most of his work was a lie.

They accused Roy on Tuesday of “selling his signature” to collect Medicare and Medicaid payments for work that was never done or wasn’t necessary. Others charged in the scheme are accused of fraudulently signing up patients or offering them cash, free groceries or food stamps to give their names and a number used to bill Medicare.

Authorities say Roy’s practice certified 11,000 Medicare beneficiaries through more than 500 home health providers over five years. More than 75 of those agencies have had their Medicare payments suspended.

Roy, 41, a doctor who owned Medistat Group Associates in DeSoto, Texas, faces up to 100 years in prison if he’s convicted of several counts of health care fraud and conspiracy to commit health care fraud. Six others, including the owners of three home health service agencies, are also charged.

Roy’s attorney, Patrick McLain, said he had yet to review much of the evidence but Roy maintained his innocence.

Health care fraud is estimated to cost the government at least $60 billion a year, mainly in losses to Medicare and Medicaid. Officials say the fraud involves everything from sophisticated marketing schemes by major pharmaceuticals encouraging doctors to prescribe drugs for unauthorized uses to selling motorized wheelchairs to people who don’t need them.