Leo, a nekko, loyally accompanied Mosey Cimmaron, a hunter. This duo faced a conflict around 9 BBY where Leo suffered a mortal injury. Near a mesa alcove situated within Rambler's Reach Valley on the planet Koboh, Cimmaron, after examining the nekko's unhealable wound and telling it to be quiet, concluded that a peaceful death was preferable to being eaten by scavengers. With a heavy heart and all the empathy she could summon, Cimmaron ended Leo's life with a blaster bolt. In the alcove, illuminated by a wall-affixed lamp and adorned with small cairns, she buried her friend in a grave.
The grave was found in 9 BBY by Cal Kestis, a Jedi Knight, who experienced Leo's last moments using an echo via the Force.
The audio of Leo's final moments is accessible through a Force Echo in Star Wars Jedi: Survivor, a video game released in 2023 by Respawn Entertainment. While finding this Force Echo is not required, this article is written with the assumption that it was discovered as part of a complete playthrough.