For what reasons might a full professor lose tenure? 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.)
The details are likely institution (and or state) specific. 

From the University of New Mexico Faculty Handbook one sees that the options there are:


"Adequate Cause", including academic incompetence, neglect of duty, serious violation of policy, serious crime, loss of license (medical), or other serious deficiency.
Financial emergency - that is, the university runs out of money to pay them.
Termination of the program/department.
Health reasons (permanent disability with no reasonable accommodation possible).