Forensic analysts have identified a new and highly potent family of synthetic opioids in the District’s illicit drug supply, a worrisome discovery in a city already struggling with a wave of fatal overdoses that shows no signs of abating. The opioids, found on used syringes examined by scientists at the D.C. Department of Forensic Sciences in September and October, are called protonitazene and isotonitazene, respectively. Experts estimate that each is at least several times more powerful than fentanyl, the synthetic opioid that has displaced heroin in many parts of the United States and is now responsible for the majority of...