MIAMI (AP) - Federal authorities indicted the largest chain of community mental health center in the country.

Court documents allege the Miami-based company billed Medicare $200 million dollars in a scam that preyed upon patients with severe dementia and altered their clinical files so they could charge for more services.

According to court records, the American Therapeutic Corporation paid the owners of assisted living facilities and halfway houses to force patients to attend programs at their seven mental health centers. Some patients also cashed in on the scheme by providing their Medicare numbers - others were "not coherent enough" to demand kickbacks.

An employee contacted authorities prompting the investigation by the Departments of Justice and Health and Human Services.