So if you do the following:
1) Get an uninitialized Vox Relay key card from the Euphoria Coast Automech Repair Center
2) Enter Vox Relay through the raptidon den
3) Initialize the keycard
4) Use the card to enter the big room in the center *without* triggering the execution cutscene
You can fight and kill Montelli right then and there - the other soldiers in the room will not aggro even if you walk right up to them. However, when you go up the lift to the room Montelli is usually supposed to be at, you'll find he's been miraculously resurrected and you have to fight him again.
