the sniper
We were careful when we briefed the sniper. The courtyard was bordered by buildings on all four sides, with a tower in each corner. Pathways ran around the perimeter and also digonally across the courtyard, with the fifth and largest tower positioned at the centre of the "X."
The sniper agreed with our assessment that the centre tower would provide the most advantageous position. The target could appear at any time at any one of the towers, such that it would be salutary to behave as though one believed in teleportation.
The focus of the sniper. So intent was he on the task ahead of him, he failed to notice that the photograph of the target we circulated after the meeting was a photograph of him.