In 2374, Rekar led a successful hijacking of the Federation starship USS Prometheus, killing the Starfleet crew, and navigating the ship into Romulan space. He and his officers were the first to prove the effectiveness of the experimental multi-vector assault mode in combat conditions by disabling the pursuing USS Bonchune.
Rekar and the other Romulans were eventually rendered unconscious by neurozine gas, introduced into the ventilation system by The Doctor, working together with the Prometheus' EMH Mark II. The vessel was then returned to Starfleet control. (VOY: "Message in a Bottle")