Back in 1978, the Kansas City police focused on James Lewis as a suspect in a missing person’s case. A serious mistake during an interrogation would come back to haunt them. But in 1982, that investigation provided valuable insight to the Tylenol task force. And it helped end the weeks-long manhunt for the extortion letter writer. Meanwhile, the Chicago Police’s main suspect, Roger Arnold, proved that he was a killer.For exclusive details about the Tylenol Murders and a transcript of this episode, visit www.chicagotribune.com/tylenolmurders.