I apologise if I am about to repeat stuff that has been discussed a lot, but I only vaguely follow this case and I had a thought whilst I was looking through the possible matches. Is it possible that FLEK changed her appearance totally, and we are looking for someone who looks very different from the FLEK that we 'know'? She went to the trouble of going through a very sophisticated identity change, so it doesn't seen beyond the realms of possibility that she would also have had extensive plastic surgery to change the way she looked. Maybe she wasn't even a natural brunette, or perhaps she naturally had lighter brown hair??