"Wagner doesn't have to defend himself. Only a guilty person would feel the need to express his innocence. Authorities sure aren't asking him to. He was never a suspect or even a person of interest so why should he?"
GNGS does not say Wagner killed Natalie Wood. What it does say is that Wagner fabricated the story that he told the police. The book says that Wagner was with Natalie Wood when she went missing, while he was having a volatile argument with Natalie.
To not answer those allegations is very disturbing, to say the least.