it was necessary that i should return without delay to geneva , there to watch over the lives of those i so fondly loved and to lie in wait for the murderer , that if any chance led me to the place of her concealment , or if she dared again to blast me by her presence , i might , with unfailing aim , put an end to the existence of the monstrous image which i had endued with the mockery of a soul still more monstrous .