Natalie Wood's sister claims to know who killed the actress 33 years ago.

"I know who killed Natalie," Lana Wood told Closer Weekly of one of Hollywood's biggest unsolved mysteries.

Natalie Wood's case was reopened in 2011 and although Lana cannot reveal details of her sister's drowning, she did claim that "according to the detectives, they think they do [know], too. There is no way the could [shut down] a case this close to being solved."

PHOTOS: Remembering Natalie Wood

Lana hopes the new information will lead to the truth coming out but every day she is reminded of her sister's tragic death, she said.

"I don't believe there is such thing as closure," she told the magazine. "Her death is ugly and painful to this day. It always will be. These days, I only go to the cemetery once a year because it hurts too badly."

Natalie Wood died after she fell off a yacht on Nov. 28, 1981, according to her husband Robert Wagner. Bruises on her body were originally said to have been from her failed attempt to climb back onto the boat.

She was nominated for three Academy Awards during her lifetime. Her death stunned the world and has remained one of Hollywood's most enduring mysteries.

The Associated Press contributed to this report.