It might look like concrete, but it's really a powerful drug rocking North Carolina.
Called gray death, the World Health Organization says it's heroin combined with other opioids, including a synthetic one known as U-47700. The synthetic substance is mixed in because dealers can buy it cheap and make even more powerful.
The DEA made it a schedule one drug four years ago. The agency said of the 46 deaths associated with it, 10 happened in North Carolina. Gray death can also contain fentanyl, and law enforcement reports it popping up all over the state
"Gray death is one of the scariest combinations that I have ever seen in nearly 20 years of forensic chemistry drug analysis," said Deneen Kilcrease, manager of the chemistry section at the Georgia Bureau of Investigation.
Gray death ingredients and their concentrations are unknown to users, and they can be particularly lethal, Kilcrease said. And because these strong drugs can be absorbed through the skin, simply touching the powder puts users at risk.
That makes an arrest this week in Raleigh even more concerning. Investigators say the suspect had grey death on him.
Some of the pills taken from Prince's estate after the musician's overdose death in April 2016 contained U-47700.
Gray death users inject, swallow, smoke or snort it. It has a much higher potency than heroin, according to a bulletin issued by the Gulf Coast High Intensity Drug Trafficking Area, an organization based in Louisiana that works with law enforcement and intelligence agencies to reduce illegal drug trafficking and availability in a six-state area of the southern U.S.