About AC's death, yes it looks suspicious on its face, because it fits everything else to assume he was killed somehow. It's an easy assumption.
But assuming AC was murdered is lazy, because it doesn't fit the mountain of proof we have that says he did indeed die by natural causes, as unlikely as that would seem.
What gets ignored is that it was NOT taken as a natural death when it happened, by LE and ME and the like.
In fact, at the point at which he died, LE didn't yet know what had happened to the children, but they had lots of suspicions. So LE and ME were hoping that AC's demise would be the key to prove that CD and LVD and their associates were murderers.
The authorities were there quickly, because 911 was called in an attempt to save him. When they saw he was dead, the "this is probably a murder" investigation started IMMEDIATELY. There was no delay -- they were looking for toxins or other some other cause that would indicate he had been murdered, and fairly sure they would find something. They did an extensive autopsy, ran every test and drug screen, asked very pointed questions of everyone, working under the obvious assumption that he HAD been killed.
Today, there's no need to wish they had AC's body to test for murder causes, because they already did that, and did it when the body was fresh, so to speak. There was nothing to find. The fact that his death was ruled to have happened by natural causes was NOT for a lack of looking, and those looks were done by the best ME types looking for anything at all that was there. Looking, looking, looking, hoping to find something, anything.
It simply wasn't there.
People die every day without being murdered, because sooner or later we all die. It can happen earlier for some, especially those who add extra issues to abuse their own health. All evidence says that's exactly what happened here. AC abused his own body in his job (iiuc he died from a blood clot, which is something that can come from long hours of travel or driving), and probably damaged his heart too with all the stress of his evil actions. And one day, it all caught up with him. What a sad waste of a life.