A third death is under investigation for ties to vaping as government scientists are still trying to get to the bottom of what is causing the illness, the Centers for Disease Control and Prevention disclosed Friday.

Public health officials have been warning the public about an illness that appears to be linked to vaping marijuana, nicotine — or a combination of both — after 215 people have have become ill and two have died, one in Illinois and another in Oregon. The third case under investigation occurred in Indiana.