Belated Justice

Quick Walkthrough
#Speak to   if on the Legion questline or   in the Curia.
#Speak to   in his cell.
#*If Legion, you can kill him to complete the quest, but do not expect much reward.
#Speak to   and  .
#*To prove Casik's innocence:
#*#Speak to Caecalia with 50 disposition and ask about 'man of honor' and  'woman on the side'.
#*#Speak to Nerasa with 50 disposition and 40 Speechcraft.
#*To prove Casik's guilt:
#*#Speak to Caecalia with 50 disposition and ask about 'woman on the side'.
#*#Then speak to Casik with 50 disposition and 40 Speechcraft to obtain his letter.
#*#Speak to Caecalia with 50 disposition and 50 Speechcraft to unlock 'property in Nibenay'.
#*#Then speak to Nerasa with 75 disposition or 40 Speechcraft to unlock 'property in Nibenay'.
#Speak to Belisatha Mede to hold the trial.

Detailed Walkthrough
Starting Out
Note first of all that completion of this quest will require you to raise your Speechcraft above 40 to complete the innocent path, and 50 to complete the guilty path. Surilie Brothers wine can fortify it by 10 if needed, but there are few other ways to boost this skill, and you may wish to train it up before beginning this quest.

If working through the Old Ebonheart Imperial Legion questline, speak to   in the Imperial Legion Headquarters in Ebon Tower. He will direct you to  . It is possible however to begin this quest simply by speaking to Belisatha, regardless of faction affiliation. She can be found in the Central Office of the Imperial Curia, behind a door signposted 'Ministry of Justice'. Ask her about 'Casik' and say that you know how to ask the right questions. Belisatha will give you a note granting access to his cell.

Neither Belisatha or Olfvur much care for the disgraced General  , with Olfvur instructing you to do what feels right, while Belisatha simply wants Casik to give up on his appeals. The man himself can be found in the dungeons under the Legion Headquarters. Speak to   just inside the dungeon entrance to gain access. General Casik is in the first cell on the left on entry. You will have to offer to help him to get the information you need - whether you intend to have him found guilty or innocent.

Press Casik for details, and then speak to the leads he gives you: his wife  , in the Curia, and his former aide,  . Caecalia is the Lord General of the Imperial Legion - the commander of all Imperial Legion troops in Morrowind, and can be found on the top floor of the headquarters in Old Ebonheart.

Caecalia Victrix
Caecalia claims that Casik attempted to bribe her, in order to sway her to his cause. She will mention another officer - if asked about it, she will reference  , who serves at the side of Casik's wife, Nerasa. If you can get her to 50 disposition, you can ask her about Casik as a 'man of honor', and then his 'woman on the side'. This reveals the existence of an Argonian lover - as it stands, this will be proof of his innocence as it contradicts later testimony. However, you should return to Casik to ask him about this, as with 50 disposition and 40 speechcraft he will give you a love letter that can be used as evidence of his guilt later.

While talking to Caecalia, if you have 50 Speechcraft, you can also unlock the topic 'property in Nibenay', which is the second piece of evidence needed to secure a guilty verdict - you will still need to obtain a paper copy of the deed from Nerasa though.

Nerasa Veren
Casik's wife, Nerasa Veren, can be found in the east wing of the Curia in Ebon Tower, with professional red-herring Rumus Stannicus by her side. Look for the door marked 'Temple Affairs'. You will need 50 disposition with her and 40 Speechcraft to have her admit that her husband might be innocent after all, which can be used to argue in his favour during the trial. If you have unlocked the 'property in Nibenay' topic by speaking to Caecalia, you can ask her about it - with 75 disposition or 40 Speechcraft, she will hand over this document, which acts as evidence against him.

Making a Case
Return to Belisatha Mede in the Curia Central Offices when ready, and note that you intend to make an appeal on behalf of General Casik. You will still have the option to choose 'I need more time' before beginning the trial. If so, she will advise you to speak to her aide, Bravilo Julianian, in the same room. He will provide advice on the case. You should have the option to note an inconsistency - that Nerasa claims Casik was with her on the night of his arrest, and that Caecalia claims he was with his Argonian lover.

You can advocate either for Casik's guilt or his innocence, but will need two pieces of evidence either way - the letter to his lover and the land deed to prove him guilty, or admissions about his possible innocence from Caecalia and Nerasa, alongside the contradiction in who he was with on the night he was arrested. Belisatha will deliver a verdict immediately after hearing your case, and will send you back to your investigation if you do not have the necessary pieces of evidence for your case.

Aftermath
Speaking to Caecalia, Nerasa and Belisatha will reveal their opinions on the verdict, either way, and copies of   will appear reacting to the results of the case. If following the Legion questline, you may now report back to   for more orders. Regardless of Belisatha's verdict, General 'Casik' in truth was guilty - being the Daedric imposter he claimed framed him all along. As for the real Casik, the truth might never be known...

Quest Stages