Rasett Milio was a scientist of the male human variety. He held the position of administrator for the HECIL division within the Galactic Empire's Tarkin Initiative. Milio's work was centered around developing force fields and containment channels to effectively "sheath" the energy discharged by a superlaser into a focused beam.
During his time on the Kyber crystal research team, Milio was seen wearing a blue and white engineering jumpsuit. This antiseptic coveralls featured the insignia of both the Empire and the Tarkin Initiative. His uniform also incorporated a tunic that changed colors when exposed to harmful radiation, along with shoes designed to prevent static electricity buildup within the laboratory environment. A chest pocket on his jumpsuit contained code cylinders, which provided authorized entry to restricted lab areas.
The first appearance of Rasett Milio was in the 2016 Anthology film Rogue One: A Star Wars Story, where Alan Rushton played the character. While credited as "Engineer" in the film, Milio's name was disclosed in Star Wars: Rogue One: The Ultimate Visual Guide, a companion book by Pablo Hidalgo that was released concurrently with the movie.