This article was originally published by ProPublica, a Pulitzer Prize-winning investigative newsroom.Reporting HighlightsPipeline: A Chinese prison is part of the pipeline that delivers fentanyl to the US, ProPublica found in a review of US and Chinese documents and interviews with investigators. Fallout: Opioid overdoses have killed more Americans than the number of US deaths in several wars combined. Permissive: Veteran federal agents told ProPublica that China has failed to cooperate and even interfered with drug investigations; China insists it has cracked down.China’s vast security apparatus shrouds itself in shadows, but...