Complex sentence: His widow, Gertrude, having remarried and now Gertrude Hullett, died soon after in mysterious circumstances on 23 July 1956, instigating the investigation into her doctor, John Bodkin Adams.
Split into simpler sentences: His widow, Gertrude, having re-married and now Gertrude Hullett, died soon after in mysterious circumstances on 23 July 1956. Her death led to an investigation into her doctor, John Bodkin Adams.