COLUMBUS, Ohio (AP) — Authorities are issuing warnings about a new and dangerous opioid combo they're dubbing "gray death" that underscores the ever-changing nature of the U.S. addictions epidemic.

Investigators say they've detected the mixture or recorded overdoses blamed on it in Alabama, Georgia and Ohio.

The drug looks like concrete mix and varies in consistency from a hard, chunky material to a fine powder.

The substance is a combination of several opioids, including heroin, fentanyl, carfentanil — sometimes used to tranquilize large animals like elephants — and a synthetic opioid called U-47700.

Deneen Kilcrease manages the chemistry section at the Georgia Bureau of Investigation's crime lab.

She calls gray death one of scariest combinations she's seen in 20 years of doing forensic chemistry drug analysis.

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