Federal prosecutors say nine more Southern California doctors have been charged for allegedly helping bilk the government in a $950 million fraud scheme.

The U.S. Attorney’s office said Thursday that the new defendants join other medical professionals and companies facing charges in the scam centered around Pacific Hospital in Long Beach.

On June 14, three physicians were charged in connection with an alleged $580 million kickback scheme on spinal surgeries and other services, federal prosecutors said today.

The hospital’s former owner, Michael Drobot, was sentenced to prison this year. Officials say Drobot paid $40 million in kickbacks to doctors and other medical professionals who referred thousands of patients to his hospital for spinal surgeries. Some patients lived hundreds of miles away.

Authorities say state and federal workers compensation insurers were billed hundreds of million dollars as part of the scheme over 15 years.