Sheriff's officials held a press conference Friday morning but were tight-lipped about what that new information was.
The department announced Thursday the case was reopened after investigators were contacted by a third party who reportedly had additional information about Wood's drowning.
Wood, a three-time Academy Award nominee, is known for her roles in "Rebel Without a Cause," "Miracle on 34th Street" and "West Side Story."
On Nov. 29, 1981, Wood was with husband, actor Robert Wagner, and her "Brainstorm" co-star Christopher Walken, aboard the yacht Splendour on a sailing trip over the Thanksgiving Day holiday. Wood went overboard and drowned.
Wood's badly bruised body was found floating a mile away from the yacht just off the coast of Catalina. She was wearing a long nightgown, socks and a down jacket, and had a blood-alcohol level of 0.10 percent, according to the police report.
At the time, Wood's death was ruled accidental by sheriff's investigators and the L.A. County Coroner's Office. But now Sheriff Lee Baca told the Los Angeles Times the department received a letter from a third party saying the ship's captain had new recollections about the case.
Dennis Davern, captain of Wood's Splendour yacht, wrote a book about her death and said that he believes Wood's death was a direct result of an argument she had with her husband right before she drowned.
Davern revealed new details about a fight that preceded Wood's death.
"Robert Wagner picked up a bottle of wine and smashed it right on the coffee table in front of Christopher and Natalie, and Robert Wagner said, 'What are you trying to do? What do you want to do, 'blank' my wife?' That's what the whole argument was about," Davern told NBC's "Today" show on Friday.
"I really suspect there was some type of foul play, if you really analyze the circumstances," said Davern.
Investigators said they had not contacted Wagner about the new information. They said Wagner was not a suspect. They did not say if they plan to interview Walken.
In a 2008 interview, Robert Wagner described his wife's final moments: "What we think is that she went outside and slipped on the swim-step and hit her head."
"And I said to Robert Wagner, I said, 'Well, you know, let's try to turn on the searchlight to see if we can see her," said Davern. "And he says, 'No, we don't want to do that right now.'"
"Before anyone contacted anyone to look for her, hours passed," said Suzanne Finstad, who wrote "Natasha: The Biography of Natalie Wood."
"A person on a neighboring boat heard screams from a woman in the water who said she was drowning, and 'Please help me,' and the whole situation just became so fraught," said Finstad.
Natalie's sister, Lana Wood, gave an interview to TMZ.com. She said she always had doubts about Wagner's story. She said Natalie would never take off by herself in a small dinghy.
"None of it made sense to me," said Lana Wood. "Simply because Natalie hated the water -- hated it, had a great fear of it.
"It goes all the way back to our darling sweet mom, who used to tell Natalie that she would die by drowning," said sister Lana Wood in the TMZ interview.
Peter Bogdanovich directed the 2004 TV movie "The Mystery of Natalie Wood."
"It must have been terrible for her," said Bogdanovich. "Because her biggest fear all through her life was water. She was terrified of water."
Thursday, the Wagner family 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."