Captain Colliard was the Captain of the Opera House Guard during the events of Thief Gold. Serving under Lady Valerius, he and his men were continually disgruntled. The captain maintained his position apparently in the hope of a letter of recommendation from the Opera House. On an excursion to kill the spiders in the tunnels beyond the sewer, Colliard &c. stumbled upon the shrine which housed the Talisman of Water. Having received word of this discovery, Lady Valerius tasked them with retrieving any treasure found there, regardless of danger. Despite at least one casualty, the talisman was brought back to the Opera House, as witnessed by Raoul.
In order to reach the shrine, the opera guards would have needed to pass directly in front of Raoul's shack. Curiously, they seem to have missed him.