Ardelon Tandro was a Klaestron general, and a leader during the Klaestron Civil War in the mid-24th century. He had a unifying legacy among his people as a hero and a legend for his role in the war. He was married to Enina Tandro and had one son, Ilon Tandro.
Curzon Dax was close to Tandro and Enina and he became close friends with Tandro.
Before the war's end, Tandro had sympathized with the rebels and decided to betray his side. In 2339, he sent a transmission with his own movements to them, implicating a select few around him who also knew those movements. He left to join them, but was killed anyway. His people, however, hailed him as a martyr who was betrayed by someone close to him. However, with official records sealed, no one was prosecuted for several years.
Tandro's son Ilon, having recently had access to the sealed records in 2369, relentlessly pursued an extradition order covertly against Jadzia Dax on charges that Dax had been the traitor, as all others had alibis. It was only after Enina's intervention, and her confession that Curzon had been in bed with her at the time of the murder, that Ilon agreed to let Jadzia go. However, Ardelon's betrayal remained a secret between Enina and Dax. (DS9: "Dax")