A former doctor at an Arkansas Veterans Affairs hospital who was accused of being intoxicated at work was indicted on multiple charges, including involuntary manslaughter after three patients who he misdiagnosed died of cancer.

Robert Morris Levy was arrested on Friday after a federal grand jury indicted him on twelve counts each of wire and mail fraud, four counts of making false statements and three counts of involuntary manslaughter, the U.S. Attorney's Office for the Western District of Arkansas said in a press release on Tuesday.

According to authorities, Levy caused the deaths of three patients at the Veterans Health Care System of the Ozarks in Fayetteville by entering misleading or incorrect diagnoses.

In one case, a patient died of prostate cancer after Levy allegedly said that their biopsy did not show any signs of cancer, according to KTLA. In another case, a patient with small cell carcinoma died after the patient was treated for the wrong type of cancer.

A third patient died of squamous cell carcinoma after Levy diagnosed him with another form of carcinoma, KTLA reported.

Dr. Robert Morris Levy. Washington County Sheriff's Department

The U.S. attorney's office said to cover up his errors, Levy altered the files of two patients to falsely claim that a second pathologist had agreed with his diagnoses.

"From day one, we made this case a priority," U.S. Attorney Duane Kees said at the news conference on Tuesday, adding that there could be other victims. "It will remain a priority until this case is closed because our veterans deserve nothing less."

Investigators did not reveal the patients' names or when the deaths occurred.

Administrators received complaints in 2015 and 2016 that Levy was under the influence of alcohol while on duty as a pathologist at the hospital, where he had been employed since 2005, according to the U.S. attorney's office.

Following the 2016 incident, he entered into a three-month treatment program and returned to work that October. He had also agreed to submit blood and urine samples for random drug testing, the U.S. attorney's office said.

All of the samples came back negative for drugs and alcohol, but an investigation revealed that he had been taking a chemical substance "that enables a person to achieve a state of intoxication but is not detectable in routine drug and alcohol testing methodology."

Kees said that the substance Levy was taking is not for human ingestion and he knew how much of it to take so it would not be fatal.

Levy was terminated from the hospital in 2018 after he was found to have been impaired twice while on duty, the Associated Press reported.

He was indicted on the charges on Tuesday and pleaded not guilty. A trial date is set for October, according to Kees. If convicted of all counts, Levy faces up to 524 years in prison.