The statute of limitations to bring a defamation claim in Arizona is one year after the cause of action accrues. See A.R.S. § 12-541.
But there are several things that could enable a plaintiff to bring a viable defamation claim after that one year statute of limitations expired. For example, since you published the statement on the internet, there could be personal jurisdiction laws that could make the plaintiff's defamation claim viable in a state other than Arizona. Also, whether the plaintiff discovered or was capable of discovering your online publication before the statute of limitations expired could be important questions in this case.
A defamation attorney would need to know more facts to give you a good answer. A defamation attorney can review your facts, analyze them, and then tell you whether the defamation claim against you is viable. As part of the attorney's analysis, he or she should determine whether qualified or absolute privileges could apply to the statement you published online in 2009.
Contact your insurance carriers to see if there is coverage for your legal defense. Consult a defamation attorney.
The general rule in Arizona is someone who negligently republishes a libelous statement about another person may be held liable for defamation within a year of that republication. See Peagler v. Phoenix Newspapers, LLC, 131 Ariz. 308 (App. 1981). Someone could republish something negligently if he or she negligently failed to ascertain the truth beforehand. The person responsible for the republication in this case could be held liable for defamation depending on the facts.