The first time u can do this is on Chapter 3, the room looks like this:
and around the corner with the actuall window displayed
good tip from Aesiwatt:
if you have the javeline gun, use this, if you like me and did not had it at this point in the game read below
take a sharp object, (if there isnt one on the ground just destroy the window to your right) with kinesis
go a step closer to the decompression window to let the enemys spawn and throw it on the necro which is running stright to you.
with a bit of luck he gets impaled through the window.
if you dont get it on first try reload last checkpoint its right before the room.
i dont take credit for the youtube video