A total of 24 people who pleaded guilty to their involvement in a massive years-long phone scam often involving fake Internal Revenue Service and United States Citizenship and Immigration Services officials have now been given prison sentences from four to 20 years.

The indictment was originally filed in October 2016 against 61 people and includes charges of conspiracy to commit identity theft, impersonation of an officer of the United States, wire fraud, and money laundering.

If victims didn’t pay up, callers threatened arrest, deportation, or heavier fines. There were also related scams involving fake payday loans and bogus US government grants, according to the criminal complaint.

The lead defendant was Miteshkumar Patel, who was given 20 years.

According to the Department of Justice, Patel was the manager of a Chicago team of "runners" that helped receive and launder the proceeds of their fraud scheme.

Patel was part of a new group of 21 defendants that were sentenced last week in federal court in Houston.

"The stiff sentences imposed this week represent the culmination of the first-ever large scale, multi-jurisdiction prosecution targeting the India call center scam industry," Attorney General Jeff Sessions said in a statement issued last week, shortly after the new sentences were handed down.

"This case represents one of the most significant victories to date in our continuing efforts to combat elder fraud and the victimization of the most vulnerable members of the US public."

The Department of Justice has set up a website to provide information about the case to already identified and potential victims, and the public.

Anyone who believes they may be a victim of fraud or identity theft in relation to this investigation or other telefraud scam phone calls may contact the Federal Trade Commission via this website.