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Wrong. You seem to have leaped from declaring that Echols was the sort of person who might have done it, to assuming he did do it. Releasing someone because the evidence against them doesn't stack up isn't a technicality you know.
I also question your original assumption. I assume you don't know the man. I don't either. I hear he was a sulky rebellious teenager with a penchant for black t-shirts, heavy metal music and Stephen King novels. I hear he had some mental health issues.
None of these things make him "the sort of person" who might murder three children. Did he have any history of violence to children, or to pets? Any record of fantasising about it? That might be the sort of background you're looking for, but so far as I know, nothing of that sort was ever presented.
On the basis of Echols being a bit of a disturbed teen, you seem prepared to assume he was indeed guilty of these three murders, despite having agreed the evidence against him didn't stack up.
I'm not impressed by your reasoning I have to say.
Rolfe.