Some random thoughts…My opinion only…
Single Perp: If this was a single perp, I don’t see there being any remote possibility of this being the only crime committed by them. For example, if this was sexual in nature, they would desire to feed this and continue down this path. I believe we would see a similar crime committed after this was transpired if they thought it was the “perfect” crime…a way not to get caught. I don’t see guilt being a factor causing a single perp to commit suicide, as their conscious has already been seared to get to the point of committing this crime. Essentially, I believe this person would be caught. And, in my opinion, would brag about this crime being unsolvable.
LEO: I have a difficult time with this angle due to the thought that over the past 25+ years there have probably been multiple law enforcement personnel who have looked into this case. At some point, if evidence was destroyed, I believe one would possibly have had an “aha” moment of the gap / lack of evidence. I know it is not always the case, but it seems that time is usually the enemy of “dirty cops”.
Multiple Perps: The difficulty in accepting this theory is coming to grips with believing that multiple people have been able to essentially “keep their mouths closed”. Which, if we were dealing with petty criminals, would most definitely go against this. Petty criminals would let something slip, and this would get them caught. So, we can and should eliminate petty criminals. Which only leaves us hardened criminals. Ones that this wouldn’t wreck their conscious. And, ones that also would be able put fear into someone if they did accidentally say something / let something slip. With all that is happening in the world today with the pandemic, we can see how fear is a great controller and manipulator. Now, this could and probably would create a huge web of people who may know something, but fear keeps them from releasing the information.
I’ve read bout the GJ3. I do not know who these were.
It’s obvious if motive was known, then this case would be fast-tracked to solving. However, motive is not known and will not be / may never be known unless justice takes place on perp(s). I think it would be foolish to dismiss the “crazy” theory / ies on this case.