earl lorence: andrea benson. how do you know it's andrea benson? it's her car registered to her.umps from cell phone towers in washington, dc. that allowed them to map the travel of the cell phones as they pinged off the towers. can you follow diana's cell phone? it bounced all around washington, dc, simultaneously with andrea's. they were together the entire day. josh mankiewicz (voiceover): by late friday, the night peggy was murdered, diana's phone stopped moving and went quiet. but andrea's phone? stephen hatchard-cole: we saw andrea's phone head out of the washington area and head up i-95. exactly the way you would drive if you were heading for peggy's house. right. josh mankiewicz (voiceover): along the way, the track phone was activated. and at 1:17 am, it pinged a cell tower right near peggy's house. what was going on? was this murder-for-hire? did andrea benson drive up to new york, call peggy on the track phone, somehow get into her house, and then murder her assistant da moran didn't think so. peggy would never have let a stranger like andrea benson into her house. so