. >> reporter: mary had met her husband, rob taglianetti, in college.ines. she was mostly a stay-at-home mom to their four kids. she told detectives that their 11 years together had been difficult at times, but something had happened that august which pushed the marriage to the brink. she was at the doctor's when her husband discovered an e-mail. his wife thanking reed for the previous night's phone sex. >> he said do you mind telling me who keith reed is? >> you knew what he had come across, huh? >> yes. >> reporter: mary who had struggled through the pain of separation once, now decided to try to keep her family together. >> i was really thinking about the kids and i just thought, you know, they deserve to be in the home with their father and the mother. >> reporter: but her husband was adamant, she says, if he was going to stay there was a condition attached. she'd have to hand over her passwords. mary told detectives he later logged on to her e-mail account and fired off a blistering message to reed. >> but it was this long thing about don't -- don'

rob taglianetti was merely the puppet, the defense would argue.ng and manipulative woman who had pulled the strings. >> all she wanted was to be with keith reed, which means she's got to get rid of rob taglianetti. she's got to get him out of the picture. >>> coming up, an angry husband, or as the defense argued, a scheming wife? >> this is the story about manipulation and exploitation. >> who was really behind keith reed's death? >>> a little more than a year after the killing of popular superintendent keith reed, rob taglianetti went on trial for second-degree murder. he pleaded not guilty. the prosecutor told the jury that this case was about an explicit e-mail that provoked a husband to kill. >> he sought out keith reed and shot him to death. >> reporter: the prosecutor laid out his case. taglianetti caught here on tape at the superintendent's school the day of the murder. a gold buick like taglianetti's spotted in reed's driveway that afternoon and the soaked piece of paper on reed's lawn? it was an atm receipt linked to taglianetti's bank ac