It turns out that the fate, at least, is a figure of speech, about how the 'fair' trial will end in finding them guilty. And it seems they're being held for more than merely questioning, though the general camp doesn't know that they actually successfully killed the priest of Cyric, effectively reducing the command's effectiveness, and placing the brunt of everything squarely on the medusa's shoulders. It was, indeed, his two allies, who had been captured; Hikass managed to escape, and was currently hiding under a mix of both magical and non-magical disguises, to protect her from both the guards, and the demons with true-seeing.