The Justice Department sued a neurosurgeon and the operators of a network of doctor-owned implant distributorships, alleging they defrauded Medicare of millions of dollars with unnecessary spinal surgeries.

The neurosurgeon, Dr. Aria Sabit, and the distributorship network, Reliance Medical Systems LLC, were the subject of a 2013 Page One article in The Wall Street Journal detailing that Dr. Sabit profited from implants he used in dozens of surgeries at a California hospital, some with tragic outcomes.

Dr. Sabit declined to comment for that article, and his lawyer didn't respond to inquiries Tuesday on the government suit. Patric Hooper, an attorney representing Reliance and its founders, said his clients "did absolutely nothing wrong" and added: "We are going to defend this thing aggressively."

The government built the civil case using cooperating witnesses wearing wires.

In one of two complaints it filed in a Los Angeles federal court, the Justice Department alleged that the Reliance network's two founders, Adam Pike and Bret Berry, operated 14 spinal-implant distributorships and parceled out ownership stakes in them to 35 surgeons who agreed to use Reliance implants.