Complex sentence: While murder was suspected at the time, no culprit was ever identified; it has been theorized that she was poisoned by a maidservant devoted to Ieyasu's legal wife, the late Lady Tsukiyama.
Split into simpler sentences: While murder was suspected at the time, no culprit was ever identified. It has been theorized that she was poisoned by one of her maidservants who had been devoted to Ieyasu's legal wife, the late Lady Tsukiyama.