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Hmm.) I believe that the clue is given at the end of each phrase spoken by the man before he kills someone.
- Let me delve into your genotype... -> genotype -> it is displayed exactly like your nickname, one to one - a coincidence? I don't believe in such coincidences.
- Your fate was determined the moment you switched to Unix, traitor! -> python, but not a snake - this is from your profile -> Python runs on almost all known platforms, from PDAs to mainframes... practically all UNIX variants.
As you can see, I have a logical mind.)