A Nevada doctor pleaded guilty on Monday despite maintaining his innocence since being arrested as part of an alleged fatal painkiller ring in Reno more than a year ago.

Dr. Robert Gene Rand appeared in federal court in Reno and pleaded guilty to involuntary manslaughter and distribution of a controlled substance.

The prosecution withdrew the other charges.

Federal prosecutors offered a deal to Dr. Rand last week and he accepted. His trial was supposed to start next week where he faced nine charge, including conspiracy to distribute and possess with the intent to distribute a controlled substance. His lawyer says he is disappointed with the guilty plea.

"I believe in my client," John Ohlson, Rand's attorney said. "I didn't think a jury of 12 would have convicted him. I just don't think it would've happened."

The Department of Justice says according to admissions made in the plea agreement, Rand prescribed an excessive amount of oxycodone to a patient without a legitimate medical purpose and not in the usual course of professional practice that resulted in the patient’s death from oxycodone intoxication. From the start of treatment, in June 2014, Rand prescribed the patient oxycodone. The DOJ says in September 2014, a doctor spoke with Rand about the patient receiving 180 oxycodone pills per month from Rand and the patient’s history. The patient was hospitalized twice. Despite phone calls, records, and encounters, Rand continued to prescribe oxycodone to the patient. The DOJ says in September 2015, Rand prescribed 45 dosages of oxycodone in 30 mg amounts, as well as Xanax, to the patient. One week later, Rand prescribed an additional 180 dosages of oxycodone in 30 mg amounts to the patient. Rand acted with gross negligence in prescribing this oxycodone and did so in reckless regard for the patient’s life.

In court Monday, Dr. Rand admitted that he prescribed Richie West 500 doses of oxycodone each month for more than half-a-year. He also admitted that it was his prescription that lead to the death of Michael Yenick.

"I've spent a lot of time with him," Ohlson said. "I've talked to just about all of his family, scores and scores of his patients who loved him. I've poured over medical records. I've looked at expert reports and I think the guy is a good man and a good doctor. However, now he's pled guilty and he's a felon."

Despite the deal, count two alone could result in a maximum of 20 years in prison. Count 2 comes with a maximum of 8 years in prison. West and the other co-defendants charged in this case have already guilty.

A sentence hearing is scheduled for October 23rd.

Both sides are asking for 60-78 months in prison, up to 87 months if he is eligible for what is known as a safety valve, which entitles him to reduction.  Rand waived his right to appeal the sentence if it is lower than 78 months.

To read our previous coverage on this case, go to http://bit.ly/2qukJP4

(The Department of Justice contributed to this report.)