In 2377, after encountering the USS Voyager, Kohlar believed that B'Elanna Torres was carrying the unborn savior, but T'Greth refused to believe this when he discovered that Torres was not a pure Klingon. He challenged Tom Paris to a death match to prove that Torres was not carrying the savior, but was unable to complete the match because he, like most of the Klingon crew, had the nehret.
He tried to take over Voyager, beaming most of the crew to a planet that which Voyager was going to transport the Klingons to settle. The bridge crew of Voyager was able to stop him. The Doctor cured him, along with the rest of the Klingons, with cells from Torres' unborn child, and the Klingons willingly settled on their new planet. (VOY: "Prophecy")