Early on in Darth Vader's career as a Sith Lord, he and the Grand Inquisitor received orders from the Galactic Emperor Sheev Palpatine to track down Jedi Master Jocasta Nu. They were tasked with bringing her to him, as she possessed knowledge of a crucial treasure for the Galactic Empire's future. This treasure was the Kyber memory crystal list containing the names of Force-sensitive children, individuals Palpatine intended to corrupt and transform into followers of the dark side of the Force. However, after Nu was captured, she unveiled the Emperor's scheme to Vader. Subsequently, Vader killed Nu, staging her death as a result of an accident, and shattered the crystal to thwart Sidious's long-term objectives.
The initial reference to the pursuit of Jocasta Nu occurred in Darth Vader (2017) 7, a 2017 canon comic book authored by Charles Soule with illustrations by Giuseppe Camuncoli. Its first actual depiction was in the subsequent issue, Darth Vader (2017) 8.