That sounds like Dijkstra, from EWD498 (1975):
http://www.cs.utexas.edu/users/EWD/transcriptions/EWD04xx/EW...
At least, the "mentally mutilated" phrase is about BASIC. The "criminal offence" phrase was actually about COBOL. You'll note that Dijkstra also had choice words about FORTRAN, APL, and PL/I, which were popular programming languages of the day.
It's tempting to say that Dijkstra was being tongue-in-cheek when he wrote this. I never met him, but based the attitude I picked up from his other writings, I'd guess that if you had asked him he'd have said he was completely serious.
And he has a point. I first learned programming in BASIC, and look how I turned out. (Well maybe I confirm Dijkstra's point. Others will have to judge.) But I do recall a bunch of characteristics of early BASIC systems that potentially led to terrible programming habits: GOTO and line numbers leading to spaghetti code; all global variables; no scope; no functions; self-modifying code (overlays); etc. All of these had to be unlearned at some point.