"As a purchaser, we didn't know we were buying Fentanyl," DEA Special Agent Christopher Hoyt said. "We were just sold it."
Fentanyl is a synthetic drug 80 to 100 times more powerful than morphine; a small amount in a dose of heroin is a danger to the user.
[DEA forensic chemist James] DeFrancesco and Hoyt said the actual number of overdose deaths linked to Fentanyl in Chicago and other cities may never be known. Routine drug screens performed during autopsies do not identify Fentanyl, DeFrancesco said.
In 2004, federal data show there were 160,000 mentions of heroin in ER visits across the country. It is unclear how many of those could have involved Fentanyl.
"No one would know," Hoyt said.