I would think that the primary focus phone-wise must be with Liz. Our phones are packed with clues about our normal and not-so-normal daily goings on. She was targeted, as evidenced by the 2am surveillance that was conducted. Now, if a killer was hired to do this there would probably be no connection to her phone records. And even if Liz knew her attacker, again there may be no phone communication between them. We have discussed geofence, but the broader the data request the less likely a judge will grant one. I still think that a major breadcrumb is the Google Maps angle. The person(s) did a preliminary scope of the area and they appeared to get lost when they left, so they were most-likely accessing a mapping app. Well, how many people prior to the crime searched for her street address? Now, I am no expert on mapping apps or even if the perp(s) used one, but they probably didn't stop by a gas station and ask for directions or purchase a old-school paper map. Check out this article on this very subject! I can only pray that 4 years later this information is still available, because Google may have a limited retention period for such data.
"In August, police arrested Michael Williams, an associate of singer and accused sex offender R. Kelly, for allegedly setting fire to a witness' car in Florida. Investigators linked Williams to the arson, as well as witness tampering, after sending a search warrant to Google that requested information on "users who had searched the address of the residence close in time to the arson."
I realize that there are quite a few mapping apps, but this information could be (or could have been) requested from each of them (such as Roadtrippers or Waze). If no searches are found, then perhaps the killer KNEW or WAS GIVEN her address, which could narrow the field of suspects.
Court records in an arson case show that Google gave away data on people who searched for a specific address.
Were Liz' street address numbers for her home prominent? If not, how did they know the address? Was that what the drive by at 2am was about?
My point is that this killer left clues, but we have no idea if, and to what degree, LE has pursued them. I think that a lot of "good" hired killers use stolen cars and stolen weapons. They minimize having any links to the crime scene. They also choose lower-risk locations, not neighborhoods with many residents and cameras. The only logical part of the equation was that it was timed very well (luckily?), and folks were not yet out and about.
Pursue the keyword search for 8623 Cedar Walk Drive, Tomball, TX-I think that the answers are there if the search data is still recoverable.