Complex sentence: According to eyewitness Boris Gudz, the execution of Sidney Reilly was supervised by an OGPU officer, Grigory Feduleev; another OGPU officer, George Syroezhkin, fired the final shot into Reilly's chest.
Split into simpler sentences: According to eyewitness Boris Gudz, the execution of Sidney Reilly was supervised by an OGPU officer, Grigory Feduleev. Another OGPU officer, George Syroezhkin, is credited for firing the final shot into Reilly's chest.