Inteview Natasha Wagner | ABCNews

Actress Natalie Wood's mysterious death 35 years ago had a profound impact on her daughter Natasha, leaving her not just with grief, but also with guilt.

Speaking from her Los Angeles home in an interview with ABC News that aired Thursday on "Good Morning America," Natasha Gregson Wagner, 45, explained that the “horrible” loss was made even more painful because she was growing up and starting to become more independent.

“I didn't want her to nurture me as much as she had,” she said of her mother, who died when Natasha was 11. “And so, you know, I went through a lot of feelings ... I felt really guilty. Like I should have been a better daughter.”

Asked how she coped with the loss, Gregson Wagner replied: “Grief is a weird thing because it's with you forever. The birth of my daughter almost four years ago has been the best balm.”

Wood was married to actor Robert Wagner. After his wife’s death, Wagner continued to raise Natasha, Wood’s daughter, and Courtney, his daughter with Wood.

“I just grew up thinking that I had two dads and that that was normal. And he is the greatest,” Gregson Wagner said of her stepfather. “I love him so much. He's been a real champion. He's been my protector. He's been my mom and my dad. He's worked so nicely with my real father. They've been so great, you know, co-parenting me.”

Wood drowned on Nov. 29, 1981, while boating with her husband and actor Christopher Walken off Catalina Island in California. The Academy Award-nominated actress, best known for her roles in “Miracle on 34th Street and “West Side Story,” was 43.

The official cause of death was determined at that time to be accidental drowning, but the lack of concrete information about the circumstances fueled speculation. The case remains one of Hollywood's longest-running mysteries.

In 2013, the Los Angeles coroner's office amended Wood's cause of death to "drowning and other undetermined factors" after a new investigation determined the actress had bruises on her body that "appeared fresh and could have occurred before she entered the water."

The cause of death was also changed from "accident" to "undetermined." Authorities have said Wagner is not considered a suspect in the case.

Wagner publicly supported the new investigation and has reportedly called Wood's death a tragic accident -- and his stepdaughter agrees with him. She discounts people’s suggestions over the years that Wagner may have had something to do with her mother’s death.

“I know he didn't,” Gregson Wagner said. “I think it was an accident.”

Gregson Wagner said she doesn’t spend any time thinking about what may have happened that day.

“The time I spend is just -- I feel sad that I don't have my mom and my younger sister doesn't have my mom. And my daughter doesn't have her grandma,” she said.

To honor her mother’s legacy, Gregson Wagner created Natalie, a fragrance based on her mother’s signature perfume. The newly launched fragrance -- featuring notes of gardenia and orange blossom -- reminds her of her mother's scent, which is one of her strongest childhood memories.

Gregson Wagner hopes Natalie will remind the world of her mother and inspire her daughter, Clover, who looks for her grandmother in the butterflies that Wood loved.

“Here, where I live, we have a lot of butterflies. And so my dad [Wagner] told me after my mom died that every time I see a butterfly that it's my mom," she said. "And so I've told my daughter that. Every time we see a butterfly, my daughter will say, ‘Momma, do you think that's grandma Natalie?’ And I say, ‘Oh, absolutely.’”

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