DETROIT (WWJ) — There has been a rising number of deaths in two southeastern Michigan counties from a drug commonly used as a painkiller for cancer patients.

An estimated 68 people have died in Wayne County — mainly in Detroit — since January, linked to the painkiller Fentanyl. In Washtenaw County, there have been nine deaths in six months.

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Washtenaw County medical examiner Dr. Jeffery Jentzen said that in all but two cases, Fentanlyl was added to another drug and the user probably didn’t know it, similar to rash of deaths from Fentanyl in 2006.

“It was contaminated cocaine with Fentanyl, now we’re seeing the Fentanyl contaminating the heroin supply,” Jentzen said.

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Jentzen said that the deaths coincide with a spike in heroin overdoses reported by the University of Michigan Hospital in March.

“Fentanyl is 15 to 20 times more potent than heroin,” Jentzen said. “I don’t think anyone would intentionally inject Fentanyl at that concentration. In overdose usage it actually stops you from breathing, it stops your brain from stimulating your breathing.”

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Jentzen believes that most of the users who died from the contaminated drugs were unaware that they had been laced with Fentanyl.