Drama or Thriller, pre 1980, featuring gum chewing thug with no remorse

I saw it on TV so it might have been a TV movie. I recall the cheerful-seeming, gum chewing killer or heavy, saying “they cut all that out of me” referring to some kind of brain washing or surgical intervention that had removed his ability to feel remorse, making him a perfect killer/thug.
I believe he gets revenge on those who made him so.
If I recall correctly he wears a cheap suit. I think it was sticks of gum, as opposed to bubble gum.