a. Reason for a third-party complaint. If a defendant contends that another person who is not named as a party in the lawsuit is fully or partly responsible for plaintiff's damages, the defendant may file a third-party complaint against that person. [ARCP 14(a)]

b. Service of a third-party complaint. The defendant who files a third-party complaint must request the clerk to issue a summons as provided in Rule 112. The defendant must serve the third-party defendant with the summons, the third-party complaint, and a copy of pleadings that were previously filed in the lawsuit, in the same manner as an initial summons and complaint, and as provided in Rule 113. The third-party defendant must file a response to the third-party complaint as provided in Rule 116 and within the time provided by Rule 114(c). [ARCP 14(a)]