48 confirmed murders. 14 years. One park. One city of 12 million people. Nobody noticed. The case of Alexander Pichushkin — Russia's Chessboard Killer — is not just a story about a serial killer. It is a story about how cities fail the people who live in them. About how investigative systems create blind spots around the elderly, the homeless, and the socially invisible. About how three survivors reported their attacks and were not believed. About how the pattern was there in the data for years,...