WHO KILLED MARK STEVEN SCOTT?

According to https://it.findagrave.com/memorial/101235583/mark-steven-scott , student Mark Steven Scott was killed by Dante’s law of retaliation inside the home of Dean Corll in 925 Schuler (=student ) Street in Houston, Texas, after being lured by accomplices Elmer Henley and David Brooks. The official side of the story reports that it was Henley who strangled Mark, then