A Dallas-area doctor was convicted Monday of illegally prescribing powerful and highly addictive opioids without a legitimate medical purpose.

Leovares A. Mendez, co-owner of Cumbre Medical Center in Garland, issued thousands of prescriptions for painkillers with no “apparent regard for patient harm,” according to federal authorities.

Following an eight-day trial, a jury found the 58-year-old physician guilty of one count of conspiracy to distribute a controlled substance and six counts of unlawful distribution of a controlled substance. Mendez, who faces up to 140 years in federal prison, will be sentenced at a later date.

The center co-owner, Cesar Pena-Rodriguez, 56, pleaded guilty last month to one count of conspiracy to distribute a controlled substance, just five days before trial was set to begin.

According to a civil complaint filed by authorities, the two doctors issued frequent prescriptions for a dangerous and often-abused cocktail of drugs called the “holy trinity,” a combination of an opioid, a short-acting benzodiazepine, and a muscle relaxer.

On 24 separate visits, the doctors wrote prescriptions for substances, including hydrocodone, alprazolam and tramadol, to undercover agents posing as patients in exchange for $250 payments, the U.S. Attorney’s Office’s Northern District of Texas said in a news release.

During the trial, attorneys showed Mendez issued prescriptions after performing only minimal or perfunctory medical evaluations, some lasting only a minute. Some undercover agents requested the medications by name with no complaint of pain, according to the release.

On several visits, Mendez coached the undercover officers on what to say if ever contacted by law enforcement about the illegal prescriptions.

Overprescription of painkillers is one of the major drivers of the nation’s opioid crisis, which has cost Texas tens of thousands of lives and billions of dollars over the years. Texas is expected to receive about $1.6 billion over the next 18 years in settlements with drug-manufacturing companies, such as Johnson & Johnson and Allergan, and prescription distributors, such as CVS, Walgreens and Walmart. About $31 million in settlement funds has been allocated to Dallas County.

In a previous statement about the doctors, the former U.S. Attorney Erin Nealy Cox said the office would “fight against doctors who are handing out prescriptions like candy.”

Neither physician could not be reached for comment Monday, and Cumbre Medical Center did not respond to a request for comment.

According to its website, the center treats patients for numerous issues, including thyroid problems, diabetes and high cholesterol and also offers laser hair removal, varicose vein treatments and 4D rejuvenation, which is a nonsurgical facelift.