Glau moves to stand next to the watchman, watching his companions search the room. "A grisly business," he mutters, stroking his beard. "I've seen naught like this in Ptolus before. You must have some stories though, sergeant. How long have you been with the Watch?"
[sblock]
Glau suspects the sergeant may not be what he appears, and attempts to determine his authenticity by asking questions that might trip up an imposter, based on his own knowledge of the city. (i.e. "What watch house were you assigned to? Oh, do you know so and so?") (Bluff, Diplomacy, Gather Info, Knowledge, Sense Motive as appropriate)
Glau also uses the conversation as an opportunity to look more closely at the watchman's clothes to see if there are any bloodstains.[/sblock]