Sad news. He was editor of the long running RISKS Digest ( https://en.wikipedia.org/wiki/RISKS_Digest), a mailing list on software failures and hazards.

Rest in peace, Mr. Neumann. Worthy of the HN's black bar of mourning for almost 5 decades of service to the software engineering community as a much needed cautionary voice about the cost in human lives and money of badly thought out code.