Leeno was a male Human stormtrooper who was under assignment to Jerec's fleet during the period of the Galactic Civil War.
In the year 5 ABY, Leeno held the rank of rating and became a member of Patrol 341 stationed on Ruusan. This patrol was under the command of Lieutenant Aagon. Leeno's role was that of gunner manning the forward cannon of the skimmer known as Z-19, with Sergeant Forley serving as its helmsman.
The patrol chose to abandon their assigned duty, seeking entertainment in the hunting of native Bouncers. However, they were ambushed by a group of settlers. Aagon and his soldiers disembarked from the skimmer, while Forley received instructions to navigate around the rock formations and trap the Rebels. Initially, Leeno's shots were scattered and ineffective, until Sergeant Forley suggested focusing fire on specific rocks to detonate them, aiming to dislodge the Rebels from their cover.
Despite their efforts, there was no apparent progress, and they then discovered the loss of their speeder bike escort, coupled with Aagon's silence. Unbeknownst to them, Kyle Katarn had led the Rebels in a flanking maneuver, resulting in the Lieutenant's death. As Forley pondered their next course of action, Leeno noticed a bouncer approaching from behind, which subdued the Sergeant and consumed his head. In a state of panic, Leeno rotated the cannon and fired, inadvertently killing both the bouncer and Forley.
Upon realizing the consequences of his actions, and deeply disturbed by the gruesome scene, he fled the skimmer screaming. The surrounding bouncers converged on him, knocking him to the ground. Approximately two minutes later, Grif Grawley and two Rebels, drawn by his cries, discovered him in this state.