I wouldn't mention it. You don't know what you could be stepping into. Maybe they are leaving on good terms, but maybe not. Besides the interview should be about YOU and your qualifications.
Tattoo these words on the inside of your wrists and consult them frequently during any and all interviews. They may want someone to do exactly the same thing as Prof. Departing, or Prof. Departing may actually be departing because they want something completely different. Etc.
Pay attention to the cues the SC (and others, in a campus interview) offer. If you feel clueless, construct open-ended questions about the program, expectations, etc. that allow them to talk.