A surgically-altered Cardassian assumed his identity in 2362, and shortly after was discharged from Starfleet after failing several crew performance reviews. "Boone" settled with his family on Volan III and operated a ladarium mining sluice. Boone's wife felt something was different about him, but believed it was due to the torture the Cardassians subjected him to. He left his wife the same year, with whom he had been married since about 2347.
In 2370, the Cardassian traveled to Deep Space 9 where he met O'Brien and recorded his voice. He used O'Brien's recorded voice to break into a weapons locker and thus framed O'Brien for the crime. Commander Sisko identified "Boone" as a Cardassian spy when it was discovered that his first molar had been extracted and that his DNA was Cardassian. Sisko then brought him to O'Brien's trial on Cardassia Prime. As soon as the Chief Archon, Makbar, saw Boone she ended the trial and O'Brien was turned over to Sisko. Boone had been only one facet of a large operation that was designed to discredit the Federation and to make it appear that they were sanctioning the Maquis. (DS9: "Tribunal")