In the "Practical Homicide Investigation: Field Guide and Checklist" manual that the LE and FBI use:

□ Examine the vehicle’s navigation system (Global Positioning System, or GPS), if so equipped, for:

   >□ Recent travel

   >□ Home location

   >□ Favorite destinations

   >□ Recent locations traveled

□ If the device is an in-dash navigation system (GPS), it is often best to seize the entire vehicle rather than attempt to remove the GPS from the dashboard.

Earlier this week, the cars were seized, so I'm making a guess, this was to study the GPS data of the cars of the victims. I'm guessing they were able to track some CCTV of where one of the vehicles was, and a white Elantra was seen having some interaction, or witnessing some interaction.

So it's just a case of wanting to speak to the Elantra driver if they witnessed something that was seen on the CCTV etc