Complex sentence: Mr. Chen is an illegal immigrant who arrived with Mr. Wong in 1936; while Mr. Wong later gained citizenship, Mr. Chen has kept away from the authorities and has not left Chinatown for the last two decades.
Split into simpler sentences: Mr. Chen is an illegal immigrant who arrived with Mr. Wong in 1936. While Mr. Wong later gained citizenship, Mr. Chen has kept away from the authorities and has not left Chinatown for the last two decades.