The Georgia Bureau of Investigation’s Crime Lab is reporting what preliminary results say is in the lethal street drug that has caused several deaths and more than a dozen overdoses in Central Georgia.

The GBI Crime Lab says tests are indicating that the fake yellow Percocet pills are a mixture of two synthetic opioids. They are reporting that one of the drugs is consistent with fentanyl analogue. Fentanyl analogue had not previously been identified by the GBI Crime Lab.

Further testing and analysis needs to be done to confirm the full identity of the drug. The GBI says the full test on the pills will require more time. They say doing tests on the pills is their top priority right now.

Authorities say this investigation is a joint effort among many groups like local and state hospitals, federal partners, and groups like The Georgia Bureau of Investigation, the Georgia Department of Public Health and the Georgia Poison Center.