It does not make sense why kill Loureiro. Sorry, but it seems very brittle as a story.
The most probably answer from the facts we have is quite simple and human... Jealousy. They both were classmates in the same overseas undergrad program, Nuno was a well established and accomplished professor in one of the preeminent tech schools in the world. While he flunked out of his program, and hasn't done much of note.