Can confirm this - if the person they kidnapped is female (I've had a male npc kidnapped before, but haven't check on this with them) and you enter the circle when the counter is below 10 minutes, you'll get a msg that X native is enraged followed by kidnapped-NPC is being attacked - the native will be attempting to rape the npc, and if you do nothing it'll happen.After a short while you'll get a 20 min countdown. You have to save her before that or she will be killed and permanently lost. Supposedly once the timer hit 10 she'll be raped.
Letting this happen does make rescuing kidnapped girls harder - because prior to this all you need to do to free them is destroy the cage they are in. Once it moves to them being raped, you have to kill both the rapist and the big guard.
So if your not comfy taking on the big guard natives.... ensure to get into the circle prior to it dropping below 10 min. Once in the circle, you can take as much time as you want, nothing further will happen till you either rescue them or fail and they die.