COLUMBUS, Ohio (AP) — A drug used to sedate elephants and other large animals, 100 times as potent as the fentanyl already escalating the country’s heroin troubles, is suspected in spates of overdoses in several states, where authorities say they’ve found it mixed with or passed off as heroin.

The appearance of carfentanil, one of the most potent opioids known to investigators, adds another twist to the fight against painkillers in a country already awash in heroin and fentanyl cases.

“It certainly is a very disturbing trend,” Ohio Attorney General Mike DeWine said.

A man suspected of selling carfentanil as heroin was indicted this week in central Ohio on 20 counts, including murder, in connection with a July 10 death and nine other overdoses that happened within hours of one another.

Some of the surviving users told investigators they thought they were buying heroin, but testing found none, Franklin County Prosecutor Ron O’Brien said. The suspect, 36-year-old Rayshon Alexander, pleaded not guilty.

Investigators are still trying to track down the source of the carfentanil. DeWine said he wasn’t aware of any thefts of the drug, which, he noted, could be shipped from abroad or produced here.