I just saw this thread and now realize this is probably the best place to aggregate my thoughts about this case.
From a post of mine yesterday:
It's all starting to make sense to me.
As per a scenerio mentioned previously in these threads and elsewhere, money was the motive. Not Kaine's life insurance, but a payout from the school district for a lost - and ultimately 'found dead' - kid. In this scenerio, Terri, possibly with the help of others, arranged Kyron's dissappearance from the school, with the intention of having it appear as if he wandered away on his own. The next step would be setting up the discovery of his body, with scene set up so it would appear Kyron's death was secondary to drowning, exposure, or some other plausibile accidental or natural cause. I would assume that Kaine was not 'in' on this plan, but anything is possible.
Ultimately, Kyron's family would be awarded a multimillion dollar settlement by the school district. Now, if all of the above has transpired as Terri had hoped, phase two of Terri's plan is set in motion. This part of her plan is to eliminate Kaine, leaving her and her two children wealthy and Terri once-again single. The hit man presumedly was contacted early-on so that he or she could possibly play a support role in the Kyron's dissappearance - or maybe Terri anticipated the public scrutiny and possible LE survellience that might be directed at her/the family after Kyron's dissapearance and just wanted to set her plan up well in advance. The hit-man would likely be informed by Terri that Kyron's dissapearance is part of the bigger plan, and that the hit should only take place if the plan is successful up to that point. If all transpires as Terri has planned, she then pays off the hit-man with her new fortune (or maybe the hitman also has an 'accident').
Unfortunately, Terri's plan falls apart sometime after Kyron dissappears. Maybe there are glitches in Kyron's removal from the school. Maybe Kyron's death does not go according to plan. Maybe people are unexpectedly present at her intended 'dump' site. Maybe Terri loses the support of an accomplice. Something doesn't go right and the plan falls apart. Kyron's body is then hidden, possible at location chosen 'just in case' - or, alternatively, an accomplice is tasked with disposing of Kyron at a remote location, ultimately well outside of the search zone.
The gardener/hit-man may have been awaiting his cue to move into action, provided that the plan transpired as Terri hoped it would. Well, according to this scenario, Terri's plan obviously did not transpire as she had hoped, and LE found the gardener/hit-man. At this point LE hatches a plan: the hit-man contacts Terri about what to do next - or about the possibility of a little hush-money. Of course he'd be wired and their conversation recorded. [I'm not sue why the presence of an undercover officer was felt neccessary by LE.] As has been reported, Terri cut the exchange short, possibly because Terri suspected a set-up by LE. Alternatively, Terri may not have suspected a set-up by LE, but nonetheless most certainly did not want any contact with the hit-man-to-be. Even if the latter was the case, and Terri did not know the meeting was set-up, the cat is out of the bag now. Meanwhile, Kaine is informed by LE, likely days in advance, and makes his planned departure with the infant daughter, and subsequently get's the RO and files for divorce.
With regard to Kyron's removal from the school (also from an earlier post of mine):
I'm thinking Terri focused her effort on making it appear to those within the school (teachers, students, other parents, etc.) that she was leaving without Kyron, but her exit with him in the truck was designed to jibe with the doctor's appt scenerio. She probably instructed Kyron to meet her outside so she could take him to his doctor's appt. If Terri suspects that Kyron is observed re-uniting with her at the truck his 'dissappearance' doesn't happen and the plan is put on hold - she can drive Kyron around the block and fake a call to the Dr.'s office: "Oh the appointment has to be cancelled? Oh yes, that's alright...Hey Kyron, whaddaya say we go get a quick bite to eat?" - then drop him back off at school.
If she's successful at getting Kyron (still alive and under the impression he's going to the doctor's) out of the school, she then can carry out her plan to make it appear he's dissappeared from school.