Complex sentence: He has a treachorous bengali assistant (Suprakash Choudhury) due to which treachery Dutta becomes blind and comes back to Kolkata without completing his research.
Split into simpler sentences: He has a treachorous bengali assistant (Suprakash Choudhury). Due to Choudhury's treachery Dutta becomes blind and comes back to Kolkata without completing his research.