Before we start, let me bash in your hopes: You cannot use with the sniper rifle you got from the previous level to shoot Hannelore while she's sitting on the balcony, finishing the level in under 30 seconds. In order to make this tactic impossible, the developers make it an objective to drag her body to a specific location first. Also it might be really hard to actually get that shot considering she'll immediately walk away once the level begins. The opportunity is there, just incredibly difficult.