A new highly potent synthetic opioid has made its way to Franklin County and is believed to have been used in the overdose deaths of a St. Clair couple.

U-47700, a research chemical, was identified as an ingredient of a synthetic heroin cocktail that authorities suspect killed Sandra “Kay” Creek, 60, and Kenneth W. Creek, 53, at their home in the 200 block of Murray Street, St. Clair, Tuesday.

According to St. Clair Police Chief Bill Hammack, officers and St. Clair EMS responded to two suspected heroin overdoses at 5:01 a.m. for two people in cardiac arrest. They were both pronounced dead at the scene.

Hammack said a powder substance was found inside the residence.

According to Sgt. Scott Reed, commander of the Multi-County Narcotics and Violent Crimes Enforcement Unit, said tests indicate the drug mixture included U-47700, also called Pink, which is about eight times stronger than morphine.

He added Tuesday’s deaths may be isolated.

“I would have expected to have seen (U-47700 again)” since Tuesday. “None has turned up,” Reed said, “but I wouldn’t be shocked if it did turn up again.”

According to Hammack there were two other adults living at the residence, but he would not comment on their status.

The cause of the deaths will be determined pending the results from the medical examiner’s office.

Reed noted that this is the first case of U-47700 in the area.

U-47700 has caused overdose deaths throughout the country and often is mixed with fentanyl, which is 50 times more potent than heroin.

Assistant Managing Editor Gregg Jones and Staff Writer Monte Miller contributed to the story.