Prince’s death was caused by the painkiller identified as fentanyl — according to the Midwest Medical Examiner’s Office on Thursday. Federal officials claim that fentanyl is responsible for an epidemic of overdose deaths throughout the U.S.

Prince Overdose Drug Fentanyl: What Is It?

The U.S. Centers for Disease Control website describes fentanyl as a man-made opioid 50 times stronger than heroin and 100 times more stronger than morphine.

The agency says illegally manufactured non-pharmaceutical fentanyl, and related overdoses, are becoming an issue.

Overdose deaths from synthetic opioids increased by 80 percent in 2014 over the previous year, the CDC said, suggesting much of the rise may reflect the greater availability of illegally made fentanyl.

In Ohio, fentanyl overdoses increased to 514 in 2014 from 92 a year earlier, and the numbers led to federal action — President Barack Obama earlier this year asked Congress for $1.1 billion in new funding over two years — to expand treatment for users of heroin and prescription painkillers.

The U.S. Drug Enforcement Administration issued a nationwide alert in 2015 about the dangers of fentanyl, saying even a small amount can kill. A painkiller widely used for terminally ill patients, it is also produced in underground labs for sale as a street drug.

It is not clear whether Prince had a prescription for fentanyl after a reported hip surgery.

Burt Kahn, a lawyer who specializes in medical negligence, said there was a potential for criminal liability if a doctor prescribed fentanyl to Prince.

“Fentanyl is a drug that would almost never be prescribed to a patient like Prince who doesn’t have terminal cancer, because the potential for overdose is extremely high,” Kahn explained.

There were more than 1,000 deaths caused by fentanyl between 2005 and 2007, mostly in Chicago, Detroit and Philadelphia, traced to one lab in Mexico that was shut down.

In April, several fentanyl overdoses reportedly hit northern California, ten of them fatal.