MIAMI — The nation’s biggest mental health scam against Medicare – totaling $200 million in false billings – ended with a quick bang Monday when the last two defendants in a long-running probe were found guilty in Miami federal court.

The health care fraud convictions of Roger Bergman, 65, a physician’s assistant, and Rodolfo Santaya, 55, a patient recruiter, capped the Justice Department’s sprawling investigation that sent about 40 South Florida defendants to prison – including Lawrence Duran, the former co-owner of the Miami-based American Therapeutic Corp.

Prosecutor Nicholas Surmacz said the two defendants participated in a “massive conspiracy to rip off Medicare.”

U.S. District Judge Jose Martinez ordered that Bergman and Santaya, both of Miami-Dade County, be placed in custody at the Miami Federal Detention Center as they await what are likely to be lengthy prison terms.

Federal agents raided American Therapeutic’s seven clinics from South Florida to Orlando in 2010, leading to Duran’s guilty plea that sent him to prison for 50 years – the longest sentence ever for Medicare fraud. Duran and his girlfriend, Marinella Valera, the co-owner and therapist sentenced to 35 years, lived in a Miami bayfront condo anddrove a Maserati when their business was shuttered after pocketing $87 million in Medicare proceeds.

On Monday, Justice Department lawyers said that Bergman and Santaya carried out the chain’s fraudulent activity at a Homestead, Fla., clinic, where patients suffering from dementia, Alzheimer’s and other ailments were exploited solely for swindling Medicare. Prosecutors said hundreds of patients were in such bad condition that they could not have benefited from any group psychotherapy at American Therapeutic.

“They didn’t even know what country they were in … they were using trash cans as restrooms,” Surmacz said in closing arguments to the 12-person jury

The prosecutor said that Bergman conducted bogus evaluations of hundreds of patients and falsified their records to dupe Medicare into believing they needed the costly mental health services.

Surmacz said the certified physician’s assistant processed the patients for a psychiatrist, Dr. Alberto Ayala, now convicted, who was sometimes out of the country despite records purportedly showing he was at the Homestead clinic seeing patients. Bergman was paid $90,000 a year before leaving American Therapeutic in 2008.