CHICAGO (WLS) -- Deaths attributed to illicit versions of the painkiller fentanyl, which are 100 times more potent than morphine, have increased over the last couple years, according to the Cook County Medical Examiner's Office.
Fentanyl analogues, such as furanyl fentanyl, acetyl fentanyl and butyryl fentanyl, are typically not pharmaceutical-grade drugs used to treat severe pain.
Since mid-December, at least seven deaths were caused, at least in part, by furanyl fentanyl, according to toxicology tests results received in April.
Since September, at least six deaths were to attributed, at least in part, to acetyl fentanyl and at least one case of butyryl fentanyl.
In all, since September, when the office began to see a sharp rise in fentanyl-related deaths, there have been at least 106 deaths attributed, at least in part, to fentanyl or fentanyl analogues. Most of those deaths - 102 of them - occurred in 2015. The data for 2016 is not a real time number, as toxicology testing can take 60-90 days.
Toxicology tests show decedents have used fentanyl alone, with heroin and with other drugs, such as cocaine.
In 2014, 20 deaths were attributed to fentanyl, according to the Medical Examiner's Office.
The Medical Examiner's Office began routinely testing for fentanyl starting in June 2015 after national trends showed a spike in fentanyl use.
Previously, the office tested for fentanyl at the discretion of the pathologist.