absence from her memorial service, nor his apparent lack of interest or cooperation as the police sought in the murder investigation. these were suspicions. but there was no physical evidence linking brad to the crime. the prosecutor would say it was because he cleaned the house. he covered his tracks well. but there it was. what was the best evidence against brad? ironic, perhaps, given the defendant's particular expertise. >> we knew we had this fabricated alibi we needed to address. >> reporter: the issue was the phone call the morning nancy disappeared. brad's cell phone registered a call from home at 6:40 a.m. when he went back to the store. proof, surely, that nancy was alive at 6:40. unless, that is, unless brad placed the call himself. brad, the world-class expert in internet phone technology.