CHICAGO—A man who police say killed three people and wounded four others during a series of shootings in and around Chicago posted nonsensical and expletive-laced videos in the days and hours leading up to the attacks. Investigators on Jan. 10 were trying to determine a motive for the Jan. 9 attacks in which police say 32-year-old Jason Nightengale apparently chose his victims at random. Police killed Nightengale in a shootout just north of the city about four hours after authorities say he shot his first victim in the head in a South Side parking garage. Those killed included a 30-year-old University of Chicago student from China named Yiran Fan, Anthony Faukner, 20, and Aisha Nevell, 46, a security guard. Wounded were a 77-year-old woman, 81-year-old woman, and a 15-year-old girl, according to Chicago Police Superintendent David Brown. Another woman was shot in the neck in Evanston, police in the suburb …