Actually, Sarah has the best rolls on scrutiny of all the party members.  Scrutiny is basically used when you're trying to detect signs of deception, or figure out someone's personality.  It's also used to operate starship sensors.  ...just because.<br/><br/>Three or more degrees of success should be enough to figure out once and for all what's up with the prisoners.  You might want to make a scrutiny roll on the guardsmen as well.