Complex sentence: In addition, in November 1925, his brother Nityananda had died; his death deeply affected Krishnamurti, who had received "assurances" regarding Nitya's well-being by prominent Theosophists and reputedly, by members of the Society's "hidden Spiritual Hierarchy".
Split into simpler sentences: In addition, in November 1925, his brother Nityananda had died. This had deeply affected Krishnamurti, who had received "assurances" regarding Nitya's well-being by prominent Theosophists and reputedly, by members of the Society's "hidden Spiritual Hierarchy".