Now I wonder if that's why he went to work - and why he went to his mom's: he has a reason for his cell phone to ping on towers along the route, to cover his tracks.
The logical thing to have done if he did do anything would have been to go to work as normal.
The cell phone pings are actually the records of phone calls btw (we can tell this because in the affidavits LE refer specically to phone calls begining and ending at particular times, which exactly coincides with the "ping" claim. That means that he was likely in those areas longer than the "ping" record would suggest.