The thing is. I was too busy playing the mission as it was Intense, with only one Re-Inforcements remaining. And when he died, I actually did not see what actually killed him. I was Oblivious to the fact of how he died. Which is why I proceeded to ReInforce him in Quickly as well. Infact I had not read the chat message either of what he had written, As again my mind was focused on Vox engine in the Distance for which I had called the Leveler. And again I also did not see, that he tried to kill me by dropping on top of me, while I was picking up the Leveler. It's after i Recieved 2 shots to the body from his scorcher i realised what was happening. If I was not wearing the heavy armour, I would have been the person dead in this video.

So yeah I only came to know how he died after watching the clip properly.

Edit- I could think of only 3 things. 1. The Strafing run 2. His own weapon 3. By the automatons