Tragically I'm not sure that at this point this case will ever be formally solved (where LE can say: "okay, here's what happened"). Imo, two of the four perps are now dead (via the murder-suicide or double suicide that took place in the Mount Lindo Cemetery); and the other two are currently in jail on other charges (and I don't see them talking). I also think LE may have less direct evidence against the two still alive (though I don't know this to be a fact).
Perhaps the best chance for the case to be solved is if LE could recover the green safe or any of it's contents, or any gas cans, or anything else that may have been taken from the house, and connect those items to the two remaining suspects. Maybe if they can show that one or more of the suspects sought immediate medical treatment for burns?
I suppose there is also a slim chance that DNA, or prints, or hair fibers might still be found on something (a recovered vehicle, clothing, or something taken from the house). Too late though for things like fingerprints or DNA on a gate
And if useful digital evidence was available, I think we'd know by now, - but who knows, maybe LE is still seeking warrants, or awaiting forensic analysis/results from some device manufacturers or apps.
This is MOO, but I think the perps may have been RR, TS, WS, and IL. All were burglars, all were gun theives, at least two of the four were rapists, at least three of them lived within a mile of the Long's house, and at least three (I think..) went to the same HS as Maggie. I think when LE went to collect DNA samples from certain young locals - they had a pretty good idea about who was involved. But I also think that the investigation was tragically (and perhaps irredeemably) bungled early on.
I think ML just stumbled onto a burglary. It may have been a burglary that had an inside component to it (where the thieves where perhaps told how to get in, and told where the safe would be be and told that they had several hours in which to attempt to open the big safe before any family members were due back home, but I don't know. I think they may have tried to get ML to give them the combination to the safe (something I doubt she knew). I think ML may have recognized at least two, and possibly three of the perps. All Jmo.
I think there were several witnesses (including those who saw the van cross the road and possibly a second tenant in a different building than the main house who saw one or more of the killers. But I don't think any of them can place the suspects inside the house participating in the murder. Maybe the upstairs tenant could recognize a voice, but I don't think you could convict someone on that.
For a while I thought this might be an inside job (possibly a family member or the tenant repaying a gambling debt by "facilitating" or turning their back to allow robbery to take place), but I'm less convinced of that now. If it was an inside job, I suppose that might be a third way to maybe still crack the case. My current thinking is that the tenant ("RP") was not involved
It is a tragic and heart wrenching case. And it's infuriating to think that ML's killers may escape justice. There was no need for them to do what they did. She had walked in by mistake. I believe there's a special place in hell for people like them, and that they'll arrive there sooner or later. All jmo