The Nationals released Kontos from his minor-league contract Wednesday.
Kontos signed with the Nationals in late May with the hope of eventually earning a promotion to the big club, but that never came close to materializing after he posted a 6.07 ERA and 1.70 WHIP across 31 appearances with Fresno. The veteran reliever is now free to sign with any organization, but with the minor-league regular season drawing to a close within the next few days, he's unlikely to pitch again in 2019.