up in diana's life for a very brief moment. >> reporter: arias calls them frequent users, people diana was calling repeatedly. >> what was also interesting to me about these frequent users is that they just had such different lives. >> reporter: diana was a suburban mom, and some of these people, well -- >> a lot of them had criminal histories living in d.c. >> reporter: remember, diana had been in d.c. for a wedding. maybe these people were, you know, those friends of the groom you have to invite? so detectives got the guest list. >> none of the high frequency callers were at the wedding. none of those people. >> reporter: and when arias looked at diana's phone records on the night of the murder, friday night into saturday morning -- >> the time of the homicide there was very little activity on her phone. like eerily quiet. >> reporter: what did that mean? diana's phone had been in d.c. that looked like a dead end.