Complex sentence: Dmitry worked as a medical doctor and was murdered 26 June 1831 during the infamous Cholera Mutiny in Saint Petersburg: the lynching mob decided that the cholera epidemic in the city was caused by the actions of the medical doctors and quarantine officials.
Split into simpler sentences: Dmitry worked as a medical doctor and was murdered 26 June 1831 during the infamous Cholera Mutiny in Saint Petersburg. The mob felt that the cholera epidemic in the city was caused by the actions of the medical doctors and quarantine officials.