Nelson did not know but in fact he is followed by a Gemini Clone, Fraus does not wanted to his enemies, which is Genesis in the most cases to attack Nelson. They most likely know that Nelson is already working with himself and Unity.
He may not be that important but in the end he is the one of the people with ability. Not counting the workers and other people, Nelson is the most important non-gemini clone individual in the whole Unity Organization.
Considering this fact, Fraus sent a Gemini Clone to follow to carriage of Nelson.
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Nelson as the carriage goes on, felt little bit sleepy and as he was about to enter sleep. A huge explosion sounded out.
Before Nelson had any chance to awaken, he felt something hold himself and then rip him out carriage,
"Where I am"