Kenneth C. Pollard did something a lot of commuters do: carried on a loud conversation on his cell phone on a train. This one, though, on the Chicago-area Metra commuter rail, ended violently.Police say passengers around Pollard began to complain of the noise, according to the Chicago Sun-Times. Eventually, the train's conductor asked him, several times, to lower his voice.Pollard refused, according to reports, growing angry with the conductor's interruptions.