Federal prosecutors say an 83-year-old Manhattan doctor has been sentenced to 20 years in prison for illegally dispensing thousands of opioid prescriptions to patients, one of whom died of an overdose two days after visiting the doctor.

Dr. Martin Tesher was sentenced on Tuesday after a Brooklyn jury found him guilty of charges that he wrote more than 14,000 prescriptions for oxycodone from 2012 to 2017 from his family medical practice.

U.S. Attorney Richard Donoghue said Tesher "used his medical skills to harm, not heal and in doing so he cost a young man his life."

During the trial prosecutors described the defendant "as a drug dealer with a prescription pad."

Tesher argued that he was trying to help his patients gradually get off opioids.