Complex sentence: It took some time, but homicide investigators learned the victim was, in fact, a Danish sailor named Fred Nielssen who had bought the watch in Hamburg from a craftsman who identified each piece he made with an engraving of his name.
Split into simpler sentences: It took some time, but homicide investigators learned the victim was, in fact, a Danish sailor named Fred Nielssen. He had bought the watch in Hamburg from a craftsman who identified each piece he made with an engraving of his name.