Jarth, a Lumerian, was an assistant to Ves Alkar, a Federation Mediator.

In 2369, Jarth accompanied Ves Alkar to the Rekag system to mediate a civil war. He was unaware that Alkar was using females as "vessels" to deposit his evil and dark thoughts so that his mind could remain sharp and pure. This process killed the female vessels. (TNG: "Man of the People")