Looking through the Shadowkeeper Item browser, I found this...
Book
Quataris' Confession
Misc6F
--This scroll contains a brief confession written by Quataris. You can use this confession to have Haer'Dalis cleared. The scroll reads like this:
"I, Quataris, do hearby swear that I have, with Malice and Forethought, framed one Haer'Dalis for the Theft of a certain Bust of Sune. I obtained the services of one Janos to steal the Bust for me. In doing so, he took the Appearance of Haer'Dalis and, without my knowledge or consent, most foully Murdered the Owner of the Bust, the gentleman Acton Balthis. I swear the Events within this Letter to be True and Clear."
The scroll is signed in the cramped quill-work of Quataris.--
Book
Writ of innocence
Misc5J
--This Writ decrees the innocence of Haer'Dalis in the murder of Acton Balthis. It is signed by Chief Inspector Brega. You may use it to obtain Haer-Dalis' freedom from the city jail.--
Misc
Bust of Sune
Misc6G
--A small but exquisite bust depicting the goddess, Sune. It was found in the possession of a shady art dealer called Quataris.--
I searched through Dan Simpson's guide and found nothing about a Quataris or a quest involving these notes. The remains of a quest, perhaps?
Apologies if this has been brought up before...