Solistein functioned as a captain in the service of the Galactic Empire, additionally serving as an aide to Darth Vader, the Dark Lord of the Sith. This occurred while Obo Rin, the debated sentientologist and xenobiologist, was authoring the Catalog of Intelligent Life in the Galaxy with Vader's support.
Solistein communicated Vader's response when Herrit, a Major and officer within Imperial Intelligence, questioned the expense reports and qualifications of Obo Rin in a communication directed to Vader. Through Solistein, Vader mandated that Rin receive reimbursement and be permitted to proceed with his project. While Herrit's doubts regarding Rin's credentials were not specifically refuted by Vader and Solistein, Solistein asserted that Vader had traveled to Sab Rufo (a world Rin alleged to have received his education, but which Herrit believed to be nonexistent).
Furthermore, Vader instructed Solistein to command Herrit to procure a Duinuogwuin cadaver for Rin to analyze, a task from which Herrit did not return alive.