So, when you get to the Dawnstar Sanctuary later in the quest-line, you are able to buy a torture chamber. There are 4 people in that torture chamber and if you keep talking to them, they will give you the location of some treasure. Unfortunately for me, I killed one of them before I got the location. Is there anyway to get the 4th treasure location?

I'm not sure. Wrong section though and try searching uesp or elder scrolls wikia. If they don't have it right now they will eventually.

Load the previous autosave of you entering the sanctuary?

...wat.

I already killed them all.

You can?...

Thanks

If you talk to the prisoners in the torture chamber you can get info out of them? I spoke to them twice and all they said was why are u doing this, or please let me go. So theres treasure eh?

You have to talk to them a few times in a row.