The tweet led to a war of words between Cox and Mother Jones magazine editor Adam Weinstein, who uncovered and wrote about similar comments on Cox's blog. The blog has since been taken down.
"Civility and courtesy toward all members of the public are very important to the Indiana attorney general's office. We respect individuals' First Amendment right to express their personal views on private online forums, but as public servants we are held by the public to a higher standard, and we should strive for civility," the attorney general's office wrote in a statement released Wednesday.
The office said it had conducted a "thorough and expeditious review" before making the decision to fire Cox.
The incident began when Mother Jones reported on Twitter that Wisconsin's riot police might be called to the Statehouse to clear out protesters. In a direct response to the message, Cox wrote: "Use live ammunition."
When confronted by Weinstein from his personal Twitter account, Cox responded: "against thugs physically threatening legally-elected state legislators & governor? You're damn right I advocate deadly force." (Weinstein's direct messages to Cox during that time period appear to have been removed from his account, @AdamWeinstein.)
@AdamWeinstein against thugs physically threatening legally-elected state legislators & governor? You're damn right I advocate deadly force
Weinstein reported on Mother Jones' website that Cox's blog also included a post saying a "teenage black thug" was "deservedly" beaten up by police, and another comparing the Service Employees International Union to Nazis.
In response to his firing, Cox wrote that his tweets had been taken out of context and were meant to be political satire.
"My post used a ridiculous tone and solution to the challenges associated with the Wisconsin statehouse protests. In no way was my post meant to be taken literally, and I don't think any reasonable person would conclude otherwise," Cox wrote in a statement. "The big question before us is whether or not public employees maintain their First Amendment rights once hired by the government."
In Wisconsin today, protesters remain camped out in the Statehouse. Early this morning, Democrats in the Assembly agreed to a deal to limit debate and vote on a contentious bill to effectively end unions' collective bargaining rights, while 14 runaway Democratic senators are still refusing to return to the state, The Associated Press reports.