The Changeling then traveled to Deep Space 9 and attended Benjamin Sisko's promotion to captain. He told Sisko a fake story of a coup on Tzenketh and that his first assignment as captain was to take him to the Tzenkethi to ascertain the situation.
On the way to Tzenketh on the USS Defiant, Krajensky installed devices which took control of critical systems in order to attack the Tzenkethi and start a war, while impersonating Julian Bashir to avoid detection from O'Brien. Bashir, meanwhile, was locked in a room. Krajensky then waited until the ship executed its attack, however, when the devices were found, the crew started a search for the saboteur. Eventually, Krajensky was revealed as a Changeling and fled. The Changeling injured several of the crew and impersonated Bashir and Odo in the process. Ending up at the engine room as Odo, he confronted Odo and confused O'Brien as he worked to fix the ship. The crew eventually regained control of the starship and Krajensky was killed by Odo. "Krajensky"'s last words were to inform Odo that it was too late, and the Changelings were everywhere.
Odo's slaying of the Changeling provoked much debate and disagreement in the Great Link. In late 2372, they had Weyoun infect him with a disease to force him to return home and be judged. His punishment was ultimately to be made into a Solid. Odo was considered a traitor by the Jem'Hadar, as he had killed one of their gods. (DS9: "To the Death", "Broken Link")