"For the first time, in Allegheny County fentanyl was found in more people than heroin," said Jeanine M. Buchanich, an epidemiologist at Pitt's Graduate School of Public Health who tracks overdose data. She said that fentanyl was found in about two-thirds of drug fatalities there and heroin in about half (many cases included both drugs). The Philadelphia Medical Examiner's Office had earlier reported that fentanyl and heroin were each found in roughly 45 percent of drug overdose deaths last year.