Complex sentence: Ivan's true identity has not been conclusively discovered, however, throughout the 1970s and eighties John Demjanjuk, a retired suburban Cleveland autoworker of Ukrainian descent, was accused of being Ivan.
Split into simpler sentences: Ivan's true identity has not been conclusively discovered, however. Throughout the 1970s and eighties John Demjanjuk, a retired suburban Cleveland autoworker of Ukrainian descent, was accused of being Ivan.