The U.S. Justice Department said Tuesday that it is stepping into a long-running lawsuit against one of the nation’s largest nursing-home chains, accusing it of systematic Medicare overbilling and sometimes putting frail, dying patients through arduous rehab schedules just to increase revenue.

The department is taking control of a whistleblower lawsuit in U.S. District Court in Alexandria, Virginia, against Toledo, Ohio-based HCR ManorCare after a yearslong investigation. The initial accusations against the company were filed by a northern Virginia occupational therapist in 2009.