A $US5 million ($A6.8 million) reward is being offered to anyone who has information that will help convict "Hong Kong Zaron" - a man accused of leading an international fentanyl trafficking operation in the US.
Fentanyl is a powerful synthetic opioid - music superstar Prince died after accidentally taking an overdose of the lethal drug in 2016.
Jian Zhang, also known as "Hong Kong Zaron", is one of 30 people accused of dealing large amounts of the powerful opioid. The reward also applies to information leading to the Chinese national's location.
The US State Department announced on Tuesday that it was offering the hefty reward for information leading to the arrest or conviction of Zhang after an overdose death in North Dakota in 2015 led them to discover the trafficking operation.
Zhang and his biotechnical company were sanctioned by the US Treasury Department in 2018, a move that was meant to prevent them from doing business with anyone in the US It was the first time the department had sanctioned an alleged fentanyl trafficker.
The Justice Department said its narcotics reward programs have led to the capture of more than 75 people since 1986. More than $US135 million ($A185 million) has been paid out since that time.
The investigation known as "Operation Denial" began when 18-year-old Bailey Henke was found dead inside a Grand Forks, North Dakota, apartment building in January 2015. Deaths from fentanyl supplied by Zhang have also been reported in North Carolina, New Jersey and Oregon. Several others suffered serious injuries, authorities said.
Fentanyl is 50 times more powerful than heroin and can be lethal even in small amounts. It's used legally during surgeries and to treat people with chronic, severe pain, such as cancer patients. Illicit fentanyl is often laced with other dangerous drugs.
The Centers for Disease Control and Prevention says that synthetic opioid-involved death rates increased by over 15 per cent from 2018 to 2019 and accounted for nearly 73 per cent of all opioid-involved deaths in 2019, most of which were driven by fentanyl overdoses.
The majority of illicit fentanyl is manufactured in China, according to federal officials.