You are asking for evidence of nothing, which is a non sequitur. It would be better, I think, to ask what evidence exists to support the possibility of an intruder. I have not learned of anything that stands close examination.
I wholeheartedly agree with this. And we have never learned of any credible evidence of an intruder that stands up to close evaluation. The OP said, "From everything which I have researched, I haven't seen definitive evidence that there was no intruder. If there were, then people wouldn't be disagreeing". And the same can be said of the intruder theory, I have never seen any definitive, incontrovertible evidence that there was an intruder. So one can continue to say that if there were, people would not be disagreeing.
I am going to go out on a limb here and surmise (assume) that the OP's reference to "enlightening information" regarding an intruder comes from the thoughts of a criminal psychologist after combing through the ransom note. I have seen several such analyses by credible experts, however an analysis even by someone well respected in their field is just that.....an analysis, an educated opinion. And while it may be based upon years of experience, it isn't proof of anything. It remains an educated opinion. We can point to a few persons involved in this case who at the time were considered leading experts in their fields, well respected with proven track records. Their work on this case has been questioned, and rightly so. If we're going to talk about objectivity, we need look no further than Lou Smit who became so convinced of the Ramsey's innocence simply by holding hands with JR while praying, which led him to concentrate his efforts on making evidence fit to his beliefs rather than remaining objective. He was fed by emotion as are many who believe IDI, that emotion leads them because they cannot fathom that parents could do what was done to JB. It's the same principle that the OP discusses, so yes we can agree that the best course is to depend upon and follow the actual evidence, the facts of this case. And there simply is not credible evidence to support the IDI theory.
Further, the analyses that I have seen come from examination of the verbiage in the ransom note and the references that are specific to JR. FBI special agent and profiler John Douglas adhered to the theory that it was someone that JR worked with who was very angry with him. This also seems to be a prevailing opinion of the analyses by criminal psychologists that I have seen. But IMO there are some big holes in this theory. JR has put forth two opinions on who the perpetrator of this crime may have been. The first was that it was an inside job. The other was that it was some "creature", a crazed pedophile. He has gone back and forth over the years as to which it might be. I think we can all agree that those are two very different profiles.
If we are to believe that this "mystery intruder" was someone known to JR, IMO that's a stretch to believe. Whoever this person was had to be very familiar with and comfortable in the home, knowing exactly how to navigate the difficult and cluttered layout and where things were located in the home. This implies that it was someone who had been in the home more than a few times, and someone whom JB was most likely well acquainted with. JR did point some fingers early on to some colleagues that he felt might be unhappy with him. These persons were investigated and cleared. IMO it's quite a giant leap to allegedly being unhappy with JR and some of his decisions, to planning to assault and murder his daughter. That's a level of anger, psychopathy and evil that surely would be noticed by others this person interacts with. That just doesn't happen overnight. IMO if someone were that angry with JR, it would be hard to hide. Usually when someone is so angry with you that they are enraged, you know about it. Someone knows about it.
The other option that JR presents is the crazed pedophile, but again this has to be someone familiar enough with the family and the house layout to navigate that night. For this theory, we are asked to believe that this person had broken into the house multiple times to become familiar and was actively watching them. And yet the neighbors, who had proven to be at least somewhat aware of the comings and goings never saw anyone who kept turning up when the Ramseys weren't around. And again referring back to the ransom note, the familiarity exhibited by the use of such terms as "fat cat", "good southern common sense", and "don't try to grow a brain" imply personal knowledge. The movie quotes are also a clue that whoever is the note's author was trying very hard to sound like a real kidnapper. Kidnappers who want the financial payoff and pedophiles have different motives, are after different results and rarely cross into the same territory. Pedophiles rarely commit their crimes in the home of the victim, they would take her elsewhere and then abandon her when they were done. Kidnappers are in and out with the victim and would never leave such a ridiculously long note written in the house while they were waiting.
And here we are 29 years later and there have been no hits to the DNA sample in CODIS, no one has ever talked or made an admission to anyone else (other than false confessions like Oliva and JMK), and no truly specifically similar crime has ever been committed to our common knowledge. Those whom the Ramseys pointed to as possible suspects all stepped up immediately to cooperate with LE and were cleared. Maybe it was a one-off. Another theory that's a little difficult to swallow. Criminals are typically repeat offenders, especially if they have committed crimes and gotten away with it.
Is this proof that there could not have been an intruder that did this? No, of course not. This is my opinion based upon what I have observed and researched over the years about this case. Just as John Douglas has his opinion, and criminal psychologists have their opinion based upon their analyses. And while many of these opinions are well educated and offered by experts who have appropriate educational backgrounds, they too have no credible or undisputed evidence that proves their theories. That's the big dilemma on these theories, is it not? The IDI theory has no evidential proof to say unequivocally and beyond reasonable doubt that there was an intruder that night. Conversely, we also cannot say with 100% certainty that there was not an intruder.
The evidence that there is while circumstantial, IMO points to a family member or members. Questions remain as to why the Ramseys withheld their cooperation from police. Questions remain as to why they misrepresented details and continue to do so. They have not been forthcoming, they have not been completely honest or transparent. We are left with what we finally learned that the GJ concluded, which for whatever reasons they DA sought to hide from the public. The GJ saw evidence that we have not. They did not buy the IDI theory even though Lou Smit was allowed to present that theory with his powerpoint presentation. They returned a total of four indictments, two for each parent. And while some choose to argue that they were not indictments for murder therefore proof of nothing, I would argue that the GJ saw that the parents were indeed responsible for the death of JB.
