Take 10 random people off the streets, start feeding terri, have the 10 randoms monitor Terri ( actions, speech, alertness) for 10 days, and majority will decide if she is in fact in that body, or just hovering over it, waiting to be freed.
by the way, i'm NOT IN FAVOR of starvation, but find it humane to lethally inject the body, if she's not in it.