In Pieces of My Life, the 78-year-old former Hart To Hart star describes the moment he discovered the actress was missing from the boat they were sailing on over Thanksgiving (Nov) in 1981, and his heartache when she was found dead in the ocean.
Publishing sources tell the National Enquirer that Wood disappeared while Wagner was arguing with pal Christopher Walken onboard Splendour, the star's yacht.
The insider says, "When Wagner went below, Natalie wasn't there. He went back up on the deck and the dinghy was gone. He knew she wouldn't have taken it because she was terrified of dark water and they would have heard its loud engine."
Wood's body was pulled from the water the following morning after the dinghy had been found floating and unused.
The death aroused suspicion at the time, and has never been explained. But Wagner maintains Wood died accidentally.
The source continues, "Having several decades to think about what happened, Wagner concluded that Natalie heard the dinghy banging against the side of the boat and went to re-tie it. But she slipped on the always-wet swim step and was knocked unconscious, rolling into the water.
"After Natalie's death, Wagner went to bed for eight days in a catatonic state of profound emotional pain and blamed himself."
The memoir will hit stores in the U.S. on 23 September (08).
Download the article from the National Enquirer by clicking here.