The "Candyman"(Dean Corll) had a lot of victims buried as well, 30 boys that they found in the early 70's. He was a homosexual who murdered teenagers in Huston. People thought that their teenage kids just left home like they often do at that age. THis guy owned a candy factory, lived in the neighborhood for years, Always gave free candy to the kids.
I don't think there has ever been a movie made aabout this case, but I could be wrong.
Wasn't "The Candy Man" one such Ronald Clark O'Brien, who poisoned his son on Halloween with Pixy Stix laced with cyanide circa 1974?
I remember the Dean Allen Corll case...he was killed by one of his accomplices, Elmer Wayne Henley, who is serving a life term in prison. Those two (and one other actor, if I remember right) were responsible by at least 30 abduction/murders, as you point out, but I don't recall that Corll had a nickname such as "The Candy Man." I do remember the case being referred to as the "Boathouse Murders," because many of the victims were buried in the dirt floor of a boat storage shed.
I think I do remember a movie.