In late November 1981, actress Natalie Wood, her husband, actor Robert Wagner, and Natalie’s then co-star Christopher Walken were spending Thanksgiving weekend aboard the couple’s Yacht, “Splendour,” when she disappeared. Her body was found hours later in the waters near Southern California’s Catalina Island.

Natalie Wood’s death was initially ruled “accidental” by the Los Angeles County Coroner’s office, who said at the time there was no evidence of foul play. But three decades later the investigation was re-opened, her death certificate amended to “undetermined,” and the late film star’s husband named as a “person of interest.”

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“There’s no doubt in my mind that he was responsible,” claims Wood’s sister, Lana.

Robert Wagner adamantly denies any involvement with Natalie’s drowning and has never been charged in connection to his late wife’s death.

WATCH: Robert Wagner On Natalie Wood: ‘We Had Everything, And In A Second It Was Gone’

Why is Robert Wagner reportedly refusing to speak to authorities and what does the fourth person on the boat that night, former “Splendour” captain Dennis Davern, claim he witnessed aboard the yacht on the night Natalie Wood died?

WATCH: Witness Claims Wagner Said ‘We Have To Get Our Stories Straight’ About The Night Natalie Wood Drowned

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Watch the video above for a recap of Thursday’s episode, then check here to find out where you can watch the conclusion of this two-part Dr. Phil, airing Friday. 

Yacht Captain Claims He Witnessed Argument Hours Before Natalie Wood’s Death