Did Ursa kill the Firelord before Ozai?

I think Ursa did kill Azulon, there's nothing that explains Azulon's sudden death except the propability of Ursa killing him.
From what I got from watching the avatar is that Zuko was going to be killed por his father, since Azulon thought it's only fair if Ozai felt the same way as Iroh did when he lost his son (Ozai suggested that he revoke Iroh's birthright.and he should take Iroh's place as the seguinte fogo lord).
Ursa the decided to take Zuko's place,
from my point of view she came up with a plan to kill Azulon, so it will be like a win win situation(Ozai the seguinte fogo lord, zuko is spared).

she was too much of a good person. i think Ozai killed his dad and Ursa took the blame and was banished. she wouldn't do something so horrible, but Ozai would. That's my theory!

I don't think so.I think the reason why Ursa had to leave was probably a different reason.Maybe she broke a law or something,and maybe that's why she was banished.
That's how I see it anyways.

well she had to sop ozai from hurting zuko so in order to do that she had to make him become the fogo lord and i dont know what the heck happened to ozai's father so i think so.

It's strongly implied that she did, anyway. Ozai said that was why she was banished (of course, I think he was lying about banishment, because that's too simple and there's too many holes in the story). Ursa said earlier in the episode "Zuko Alone" that Azulon was in perfect health, and in the end of the episode, it turns out he died. segundos after his funeral, Ozai was crowned fogo Lord.. So he apparently told them or wrote down that Azulon wanted him to rule and not Iroh.

I think she did kill him, but I'm iffy on the banishment.

she didnt kill him because he went in to war with the avatar and he waz defeated but aang didnt kill so hes still alive hes just in jail but ursa left bc she needed to protect zuko and weve havent seen her since

Ursa was banned because Zuko was supposed to originally be killed por the fogo nation something. But instead, Ursa took his place and instead banished her. That's why shes not there. She didn't kill anyone. fogo Lord Azulan died of old age, not por murder.

I think what happened was in order to save Zuko she made a deal with Ozai that if he didnt kill Zuko, she would help him become fogo Lord, so I think they murdered him together but not before rearranging his will, and then he banished her for killing the fogo Lord

I think she did kill Firelord Azulon. Remember ozai told zuko in the ep, in season 2 ''zuko alone'' that his mother, Ursa committed some attrocities and she was banned. we all know ursa loved zuko very much and when she learnt that he was going to be killed she decided to kill him <azulon> first. Remember her last words to zuko? ''everything i have done is to protect you <including murder> never forget who you are!''
There is a high possibity that Ursa killed her Father-in-law.

She probably did but I wonder how she got Azulon to change succession. He seemed pretty adamant that Iroh was to be fogo Lord and that Ozai should be punished for even suggesting he betray his first born. What leverage did Ozai and Ursa use over him? (I'm fairly certain that they both worked together somehow to kill him.)
Couple things I can think of. The first route is the mais clean-cut and boring of the two: the will Azulon left declaring Ozai fogo Lord was a fake, made por Ursa or Ozai or some(likely silenced) forger.
But the segundo one is so much mais interesting to me. What if Ursa was half waterbender and a bloodbender besides? And she controlled him into composição literária that will and then killed him using bloodbending? While there's little evidence that really points in that direction it does make a certain degree of sense. After all, Ursa's mother/father was a child of Roku's and considering Roku was the avatar, they probably had a different perspective on the world and maybe even met people from other nations. And maybe, just maybe, it would explain why Ozai seemed so cold toward his wife and indifferent about her disappearance. It would also give her a place to go where she could be relatively incognito: the Northern Water Tribe. Or maybe she had a bloodbender friend from one of the water tribes who helped her with the deed instead. It's grasping straws I know but I just don't see how else they might have been able to make Azulon create a will like that. Sure they could have tortured him, but that would be too suspicious and obvious.
And just a note to anyone who nay-says the fact that she killed Azulon: there's a clue within pretty much the first minuto she's on the screen. Zuko throws pão at a turtle-duck chick to show his mom "how Azula feeds turtle-ducks." The mother pato comes and bites his leg. Ursa detaches the bird and says "that's what Mom's are like. When you bite their babies, they are going to bite you back." What do you think Azulon was doing, ordering Zuko be killed por his father? He was attacking Ursa's baby. So she "bit him back." Not only that but there's too much coincidence around Azulon's death for Ursa not to have been the one who killed him. Less than a dia after Ozai's told to kill Zuko, Ursa shows up in the middle of the night to impart some last minuto wisdom and a fair well to Zuko. In the morning Azulon's dead, Ursa's gone, and Ozai's semi-emo acting. Not only that but Ozai pretty much flat out SAYS she killed him when Zuko confronts him on The dia of Black Sun.
I suppose I get why you wouldn't want to believe she'd do something like that but her character was devoted to protecting her son. She wasn't some sweet little angel, like all the characters on the show really. Mothers can be tough as nails when their bebês are threatened.

TL:DR? Wondering if it's possible Ursa is a bloodbender, see above for explanation, and if you think Ursa didn't kill him you're either naive or in denial.

On the dia of Black Sun, Ozai finally shed some light on Ursa's mysterious departure to Zuko, and revealed that Azulon did indeed order him to kill Zuko. Ursa learned of this, and wanting nothing but to protect Zuko, she proposed a plan to Ozai, fully aware of the consequences, which she accepted. The specific details of the plan were not revealed, but it resulted in the death of Azulon, Ozai's ascension to the fogo Nation trono in Iroh's place, and Ursa's banishment from the fogo Nation for doing "vicious, treasonous things".[4] <<<<<<<< Got this from wikipedia :/ from this information it explains she did although the makers of avatar are making a new book Called "the search" that continues off from the last episode and they are working on a chapter about the ursa mystery coming this 2013 ;) check it out