Despite the fact that Injun Joe is a known murderer, a group of women from the village draft a petition to the Governor to pardon him—an example of situational irony. Readers expect the village to stand behind the families of the victims, but, instead, they go into “deep mourning”:
The petition had been largely signed; many tearful and eloquent meetings had been held, and a committee of sappy women been appointed to go in deep mourning and wail around the Governor, and implore him to be a merciful ass and trample his duty underfoot. Injun Joe was believed to have killed five citizens of the village, but what of that? If he had been Satan himself there would have been plenty of weaklings ready to scribble their names to a pardon petition, and drip a tear on it from their permanently impaired and leaky waterworks.
Here, Twain is highlighting (and satirizing) the hypocrisy of people whose sense of morality is warped. Rather than truly acting morally (by caring for the people who were affected or thinking of the good of the town), these women want to perform a certain kind of piousness that is more about being seen as moral and caring rather than actually being so.
Twain also uses verbal irony to communicate his critical judgment of these attention-seeking grievers, describing how they would seek a pardon for “Satan himself.” He does not believe this, of course, but he uses sarcasm to make clear his critical assessment of them.