During the Galactic Civil War, diminutive spy droids known as scout transmitters were utilized. Their extremely small size allowed them to be held in the hand of an analysis droid. These devices, characterized by their circular form and green plating, could be affixed to walls for silent observation, yet possessed the ability to produce a form of audible speech to interact with other droids.
Following the mysterious death of Padmé Amidala in 19 BBY, Sabé, the former handmaiden of the senator, infiltrated Amidala's apartment on the planet of Coruscant in order to gather surveillance recordings, leaving a scout transmitter there. In 3 ABY, while investigating the senator's death, Darth Vader, the Sith Lord, and his forensics droid, ZED-6-7, entered the apartment and discovered the droid. ZED-6-7 proceeded to analyze the scout to ascertain its allegiance, despite the transmitter's objections. The information extracted from the droid led them to a compound located on the planet Vendaxa, where they encountered Sabé.
The first appearance of scout transmitters was in Darth Vader (2020) 1, which was the initial issue of the comic-book series Star Wars: Darth Vader. Greg Pak wrote the issue, Raffaele Ienco provided the illustrations, and Marvel Comics published it on February 5, 2020.