Like I said, we really need to be careful with the "turning off" and "no activity". There is a difference.
Again from preliminary hearing:
Q Turning your attention to February 6th, 2010, Saturday,
what did your analysis reveal on that day?
A The first phone activity is at 10:46 A.M. It contacts a
tower in the Victorville area near Interstate 15.
The next activity is at 11:30 A.M., and continuing
through 11:52 A.M, contacts the cell tower in the Oro Grande
area just north of Victorville in the High Desert, near
Interstate 15.
11:53 A.M., contacts a cell tower a little bit to the
south, back up near Victorville.
THE COURT: What time was that?
THE WITNESS: 11:53.
And 12:49 P.M., contacts a cell tower in the Victorville
area.
And then at 1:30 P.M., has contact with the cell tower in
the Oro Grande area, again from a direction pointing to the
south in that case.
This is the only information that we have for now about towers and times. Since it's from a court hearing, it should be more reliable than most news stories or blogs haha
If you want to read it all together it can be found on this page:
State of California VS Charles Ray Merritt: Part Three - Transcript of Charles Merritt Preliminary