The song 'Aero Zeppelin' by Nirvana (see here for Youtube video link) begins with a calmer introduction that has a 'creepy' feeling, due to the occurrence of the tritone. I have tried to analyse the mode the song is in, and I think it is in D# Locrian based on the notes I can hear (all the notes seem to fit in the Locrian D# scale). But I am not familiar enough in music theory to be sure whether that is correct. I was looking for examples of songs that used the Locrian mode and I thought this could be a possible candidate.
So is this part of the song really in Locrian, and if not, what mode is it in?