Recently, a full professor at my university lost their tenure and had their employment with the university terminated. I have never heard of a tenured faculty member "being fired" before. I am not sure why this happened or what the former professor did that resulted in this outcome.
I know that assistant professors can be denied tenure for poor performance. But for what reasons might a full professor (or an associate professor) lose tenure?
(In this question I use US-centric academic ranks. An assistant professor is tenure-track, an associate professor is tenured, and a full professor is tenured with a slight increase in pay/benefits/responsibilities.)