>> then investigators checked the code numbers used to deactivate the porcos' home security system on the night of the attack. the security system's computer showed that whoever deactivated the alarm, and presumably cut the phone lines, was someone known by the family. >> the alarm had been disarmed at approximately 2:00 in the morning. so, this was the master code that was used, which was the code the family had, as well as possibly one or two other people. >> so, despite joan porco's claim that her son, christopher, wasn't responsible for the attack, investigators took a fresh look at where he was on the night of the crime. christopher claimed he was in his dorm room 220 miles away. investigators obtained security