Who killed Mrs. Joe?

Mr. Joe died after a long period of suffering caused by Orlick's attack.

But I suppose there is a shock of regret which may exist without much tenderness. Under its influence (and perhaps to make up for the want of the softer feeling) I was seized with a violent indignation against the assailant from whom she had suffered so much; and I felt that on sufficient proof I could have revengefully pursued Orlick, or any one else, to the last extremity.