Agree in most cases BUT I think the events warrant the collection of evidence immediately without a search warrant due his death and the degree of his crime.... such collection may be inadmissible later but speed is of the essence in such cases “per my experience” with acts of terror. Courts can determine after the fact legality .......
The problem with that scenario is the legal doctrine of "the fruit of the poisoned tree." If this is the root of the concatenation of evidence that leads to other conspirators who were definitely were involved in the crime, and the investigators ONLY found them because they were in that iPhone which was opened without a proper search warrant, then ALL subsequent evidence WILL BE THROWN OUT as fruit of that original poisonous tree. . . too bad, so sad, but case law requires it. The perps walk.
We may know beyond a shadow of a doubt they did it, and find other evidence later because we WILL NOW LOOK FOR IT, but had we not known to look for it from the evidence found in that iPhone we would NEVER have known about them. . . and even that independent evidence would still be "fruit of that poisoned tree." They still walk.
That is why it HAS to be done with the right legal boxes checked. Otherwise even a first year in practice defense attorney would find it a cake walk to get his client a directed verdict of "Not Guilty," if it has gone to trial, or a dismissal with prejudice if the case has yet to go to trial, preventing the case from ever being brought by the state.