I'm starting the game following the guide to get the Good Samaritan, on my way for the second mission (after Buck's Story) I confront 3 brutes gathering the Engineer, at first I just want to kill the Brutes and after I did that the Engineer all the sudden chase after me and killed itself. Just to be sure, I restart the mission (which is from the last point of the checkpoint) and just go pass through them from the back without confronting them.
However, as I finished doing the next mission, I went back to the area of the first engineer just to see if it's there, but it wasn't there so I'm totally confused of what happened to it.
Should I start the new game all over again or just continue on playing?
EDIT: Nevermind, it just popped during the search for Dare
100% : 423
/ CLOSE : 5
/ NOT THAT CLOSE : 5
Reached to 300,000G @ 16/8/13
Achieved 10,000 achievements @ 28/12/12