seven o'clock
`` Nothing , Monsieur le Préfet . Otherwise , Sergeant Mazeroux and I would have given the alarm . '' `` Was the garden door shut ? '' `` It must have been , as we had to unlock it at seven o'clock . '' `` With what ? '' `` With the key on the bunch . '' `` But how could the murderers , coming from the outside , have opened it ? ''