The November 1981 drowning of actress Natalie Wood in the waters off Southern California’s Catalina Island was initially ruled an accident by then Los Angeles County Chief Medical Officer and Coroner, Thomas Nagucci. Then, after three decades, the investigation was reopened in 2011. The circumstances of the film star’s death were changed from “accidental” to “undetermined.”

Watch: Natalie Wood Drowning: New Accounts Emerge Three Decades After Star’s Last Voyage

TELL DR. PHIL YOUR STORY: Outrageous news story in your town?

At the time of her death, Wood and her husband, actor Robert Wagner, along with Natalie’s then co-star Christopher Walken had been spending Thanksgiving weekend onboard the couple’s 55-foot yacht, “Splendour.” Witnesses reported at the time, hearing the two men arguing in the hours before it was discovered the actress had gone missing.

Watch: Former Yacht Captain Claims To Recall New Details From The Night Actress Natalie Wood Drowned

Robert Wagner was named a “person of interest” when the inquiry resumed three decades after his wife died. He has long denied any involvement in Wood’s death and has never been charged in connection with any investigation regarding her drowning.

“I think the investigation was mishandled from the beginning,” claims Natalie’s sister, Lana Wood, in part one of a two-part episode airing Thursday. “Conspiracy is a bit far-fetched but were things covered up and overlooked purposefully? I’m sure they were.”

What new information do the Los Angeles County investigators say they’ve received since the investigation was reopened? And what does one witness who was onboard the couple’s yacht the night Natalie Wood drowned now claim he heard?

Check here to find out where you can watch.

TELL DR. PHIL YOUR STORY: Have a story in the news?

Actress Natalie Wood’s Sister Claims Former Brother-In-Law, Robert Wagner, Has ‘Something To Hide’ In Drowning Investigation