The department announced Thursday that the sheriff's homicide bureau decided to examine the case again after investigators were contacted by people allegedly in possession of additional information about Wood's drowning.
Natalie Wood Wagner drowned off Catalina Island on Nov. 29, 1981. The sheriff's department and the county coroner's office conducted an investigation at the time and ruled the drowning an accident.
Friday morning, investigators will officially re-open the case.
Wood was a child star in some of the most famous Hollywood movies of all time, including "Miracle on 34th Street." She was a teen star in "Rebel Without a Cause." As an adult she starred in "West Side Story" and "Gypsy."
Her marriage to the dashing Robert Wagner made them Hollywood's most glamorous couple.
The sheriff's department confirmed homicide investigators were recently contacted by sources claiming to have new information on her drowning.
Wood was aboard her yacht "Splendour" with Wagner and actor Christopher Walken, her co-star in the film "Brainstorm," when Wood apparently went overboard and drowned.
Dennis Davern is the man who captained the yacht that night. He wrote a recent book about it called "Goodbye Natalie, Goodbye Splendour."
Davern was also interviewed in the current Vanity Fair article "Natalie Wood's Fatal Voyage." It's believed the captain's new comments may have triggered the new investigation.
Thursday's announcement was news to Wagner. His publicist released a statement:
"Although no one in the Wagner family has heard from the L.A. County Sheriff's Department about this matter, they fully support the efforts of the L.A. County Sheriff's Dept. and trust they will evaluate whether any new information relating to the death of Natalie Wood Wagner is valid, and that it comes from a credible source or sources other than those simply trying to profit from the 30 year anniversary of her tragic death."
Theories have been around for years, along with plenty of gossip and speculation.
Wood's death was ruled accidental by sheriff's investigators and the L.A. County Coroner's Office following her death.