Complex sentence: Sreebala begins to uncover clues about her father's accident, which had rendered him mentally challenged.Doubting that Xylex may have played some part in the scheme, Sreebala loses her trust in him.
Split into simpler sentences: Sreebala begins to uncover clues about her father's accident, which had rendered him mentally challenged. It appears that Xylex may have played some part in the scheme, and Sreebala loses her trust in him.