Antoine de Massy, 29, a member of Monaco’s princely family, was found dead in a square on Sunday, police said. His family had previously reported the man missing. Investigators are now working to establish the circumstances of his death. Police detained a man captured on video near de Massy shortly before he died. Prosecutor Stéphane Thibault said the detained man does not have suspect status, and it is also possible the death occurred without third-party involvement. On the night before Sunday, de Massy was seen staggering as he left a nightclub, according to informed sources. Prince Albert II and Princess Charlene expressed shock over his death. Antoine de Massy was the grandson of Princess Antoinette, the older sister of Prince Rainier III, Albert II’s father.