Ches'sarro Seeto was a Bajoran collaborator during the Cardassian Occupation of Bajor. His name was the first to appear on a list of eight sympathisers held by Vaatrik — who acted as the middleman between such individuals and Gul Dukat — hidden in his chemist's shop aboard Terok Nor. Kira Nerys later claimed that the Bajorans listed were helping to sell out the Bajoran Underground to the Cardassian Union.
After the Occupation of Bajor, he was a mining engineer who was active in charity work for war orphans. Furthermore, as a collaborator, Seeto had been able to maintain a substantial amount of money throughout the Occupation. Although former members of the Bajoran Resistance were not certain, several affiliates of Kira Nerys suspected Ches'sarro had colluded with their enemies when the Occupation was in place.
In 2370, during Rom's attempted recollection of the list, he recalled his name as Ches'so, from which Kira was later able to determine as Ches'sarro. He was found drowned in a pond on his property. When Odo learned about the engineer's death from Kira, he requested from her that she advise the medical examiner that Odo wanted an autopsy on the body and his death be treated as a suspected homicide. Odo believed that he was murdered by Vaatrik Pallra after he questioned her about the identity of Ches'so. He suspected the motivation for the murder might be the elimination of a lead for investigators. (DS9: "Necessary Evil")