Hyo Jin Moon was 45. Moon's United Press International was the first media outlet to report this.
Although Hyo Jin Moon was initially groomed to run the Unification empire after his father's death, his substance abuse and bizarre behavior (watch the 60 Minutes segment) led to his younger brother Hyun Jin "Preston" Moon to be next in line to be the patriarch of "The Perfect Family." I have written about Hyo Jin Moon's marriage to Nansook Hong (also here), a 15 years-old girl (the illegal marriage was arranged by Sun Myung Moon).
Hong wrote of her years of abuse with Hyo Jin Moon and the Moon family in her memoirs, In the Shadow of the Moons: My Life in the Reverend Sun Myung Moon's Family.
Here is the video of a Boston-area news report on Hyo Jin Moon and the 1998 60 Minutes interview with Hong.