We always hear about a victim's cellphone that pings off a cell tower or two or three and being able to triangulate a location off of the pings.
So, I am sitting here thinking about this a little differently. Since you do not have to be talking on the phone for it to ping a tower, it just needs to be turned on. I may be incorrect here but it is my belief that some cellphones do not have to be turned on as long as the battery is charged and in the cellphone and it will still ping a tower.
Since the cellphones, towers, usage, billing, etc. are all computer recorded, I am thinking that if you have a window in time in which the crime took place, identify the three cell towers nearest to the crime scene as well as their identifiers and all the cellphone numbers pinging these three towers in your window of time that the crime took place extending each end of the time window by xx minutes, hours or whatever you decide. You would now have a cellphone number list of cellphones that were in the area during the time in which the crime was being committed. You will able to see if it was moving or stationary and triangulate the locations closest to the crime scene.
Using the cellphone number list and looking up the phone numbers you have a list that has names & addresses available through business records. Using those names you can check with the DMV and get vehicle descriptions and license plate into.
Is this currently being done? I suspect it is not or they would likely have a person of interest in custody using this methodology.