Yadamonerk said Shugo laws demanded all possible suspects be investigated in Gestanerk's death, including Hecuba's claim that Hamerun the Leech was responsible. Although suspicious when Yadamonerk stopped you from reporting this to the Guardians, you accepted his offer and got rid of Hamerun the Leech. Yadamonerk was happy to have avoided punishing the wrong person--you think.