Alright this is a little complicated, I know I had trouble with it at first. And please be aware this may contain small quest spoilers!
You get the quest after The Prosecution quest in mithira. How to get that quest, walk around mithiras streets until you see a blood coated street. Walk on it and so on gose the first quest. Now for the Confession Quest.
You are forced to give the judge 1000 gold until you find the guard. First, visit the witness, a streetwalker, on that same street you were just at. (covered in blood) Remeber, this is a timed quest, you have 48 hours to complete this quest- or else face the Champion of Mithira.
Talk to the streetwalker and follow her directions to the Cult Leaders house. Pretend or actually join the Cult if you wish, that dosent matter. Follow the cult leaders instructions and go to the north west of mithira. Go to the large hut-house and open it. Use the beard you got from the cult leader on him.
--The Choice is Yours--
Choose to ask him to confess and gain more fame, and get back your money!
Choose to ask for the vial of blood and give it to the cult leader for less fame, one amulet of the eye, more respect with the cult leader. But also face why happens for doing this...
--Outcome of out of time, or helping the cult leader--
You face the champion of mithira. He was relatively easy for me, but I was lvl 11 when I battled him, so grab lots of pots of you decide to help the cult leader. If you run out of time, tough luck. (Although I used no pots) You auto-teleport to the Jude if one of theese events occur. No option.
Well, I hope this guide helped! If you need more help or details reply please!
-Lord Dim