Child support can be very high, as much as rent in some small cities. It can definitely be a motive for murder for some people. I think it plays a role here, as well as the wrath of NL, possible break in his relationship with his child and the whole affair being made public (all of which are happening anyway.
Also, I think we may find that CL led LE to those specific mines due to his online searches, his phone and/or electronic trail. Etc.
OT, watched a Dateline last night involving college-aged people. The murdered had his phone on Airplane Mode for five hours (during the time of the murder) but LE was able to see he used the Flashlight App for 45 minutes while he would have been burying the body (later found) after buying the "usual" items...shovel, duct tape, etc...all on video. So you never know what LE knows or is holding for later court appearances.
Jmo