"Interrogee"

That's a new one on me, though the meaning is clear.

Of the 119 Westlaw case references, 40% are from Louisiana and Ohio, with the remaining 60% coming in dribs from a bunch of other states. "Interrogatee," which most closely mirrors the familiar "interrogator," is slightly less common, with 71 Westlaw case references. (There are >5000 references for "interrogator.")