C433 Chief culprit
In fact, even at this step, Yang Sha only thought that her conclusion was inference.
After all, there was no evidence to prove the truth. It was all based on guessing, but since there were no other clues, this deduction was somewhat reasonable.
Yang Sha had also said that the chances of Li Duan killing Li Fen with his own hands was eighty percent, so it wasn't completely certain.
Hence