A former Columbia University professor who recentlyleft several suicide notes at his Harlem apartmentwas found dead inside a rental car in upper Manhattan Thursday night, cops said. Bruce Chadwick, 48, was discovered unconscious and unresponsive inside a red Zipcar near W. 123rd St. and Riverside Drive. shortly after 11 p.m., police said. His cause of death was not immediately known but a source told the Daily News the case was being investigated as a suicide.(nydailynews.com)…[+]