A former Huntsville doctor, who was the nation's highest Medicare prescriber of opioid painkillers, pleaded guilty today in federal court to $9.5 million health care fraud and illegally writing prescriptions.

Shelinder Aggarwal, 48, previously reached an agreement with prosecutors to serve 15 years in prison, forfeit his former clinic and pay $6.7 million.

U.S. District Judge R. David Proctor accepted Aggarwal's guilty plea today, but reserved his decision on whether to accept the 180-month prison sentence until Aggarwal's sentencing hearing, according to U.S. Attorney Joyce White Vance's Office. Vance is the U.S. Attorney for the northern district of Alabama.

"The agreement between Aggarwal and the government is a binding plea agreement, so either party may withdraw from it if the court does not accept the stipulated sentence," White's Office said in a news release. The announcement was made in conjunction with FBI Special Agent in Charge Roger C. Stanton.

Aggarwal was a pain management doctor who operated Chronic Pain Care Services on Turner Street Southwest.

Aggarwal earlier repaid $2.8 million to Medicare and $45,843 to Blue Cross following audits, according to the plea agreement.

The health care fraud involved $9.5 million in unneeded and unused urine tests, according to the news release.

In 2012, about 80 to 145 patients a day visited Aggarwal's clinic. Initial patient visits typically lasted five minutes or less, and follow-ups two minutes or less. Aggarwal did not obtain prior medical records for his patients, did not treat patients with anything other than controlled substances, often asked patients what medications they wanted and filled their requests, prescribed controlled substances to patients who he knew were using illegal drugs, and did not take appropriate measures to ensure that patients did not divert or abuse controlled substances.

The plea agreement summarizes an interaction with a patient, which was captured on video. In it, Aggarwal notes that the DEA viewed him as the "biggest pill-pusher in North Alabama" and that many of his patients were "dropping like flies; they are all dying."

Aggarwal surrendered his Alabama medical license in 2013, along with his Alabama and federal Drug Enforcement Administration certificates to prescribe controlled substances, after the Alabama Board of Medical Examiners initiated an investigation.

According to the Prescription Drug Monitoring Program for Alabama, Alabama pharmacies filled about 110,013 of Aggarwal's prescriptions for controlled substances in 2012. That would equal about 423 prescriptions per day if he worked five days a week, and resulted in about 12.3 million pills. The PDMP rated Aggarwal as the highest prescriber of controlled substances filled in Alabama in 2012, with the next highest prescriber writing a third as many prescriptions.