A man who owned a Corona pharmacy was sentenced to over five years in prison after he admitted submitting more than $13 million in fraudulent insurance claims for expensive medication.

Thu Van Le, 42, pleaded guilty in July to one count of health care fraud, the Orange County Register reported Tuesday.

Le admitted paying kickbacks to “marketers” who submitted claims for tailor-made drugs known as compounded medications, according to court documents. But the specialized formulas weren’t necessary, prosecutors said.

“The prescriptions were supposed to be for unique patient needs, but they instead were formulated to maximize reimbursements and were prepared on an assembly-line basis,” the U.S. Attorney’s Office said in a news release.

Most of those customers received cold calls from marketers who obtained their medical information and promised free medication, prosecutors said. Some weren’t contacted at all before receiving expensive drugs that they did not order.

Le, who owned a pharmacy in Corona, was one of six defendants indicted by a federal grand jury on June 21, 2018.

“In court, he expressed extreme remorse for what happened and took full responsibility,” Le’s attorney, Michael Khouri, told the Register.