What to know about Natalie Wood's still unsolved 1981 drowning death

— -- The drowning death of Natalie Wood remains one of Hollywood's biggest mysteries.

After nearly 40 years of speculation, detectives from the Los Angeles County Sheriff's Department, in a last-ditch effort to solve the case, are making a final push for witnesses to come forward, including Wood's then-husband, actor Robert Wagner, who has been called a "person of interest" in the case.

"We want to talk with Robert Wagner," Homicide Bureau Lt. John Corina told reporters Monday.

"He's a person of interest because he was the last person with her before she went in the water," Corina added. "He was the last person with her, arguing, before everything went quiet."

Blair Berk, Wagner's attorney, did not immediately respond to ABC News' request for comment.

In 2013, Berk said that Wagner had nothing to do with the death.

"After 30 years, neither Mr. Wagner nor his daughters have any new information to add to this latest investigation," she said then in a statement, blaming publicity seekers for exploiting the case.

At the news conference Monday, detectives admitted that they are running out of time to finally solve the mysterious circumstances around Wood's death.

"Our biggest challenge is time," Corina said. "Many witnesses have passed away, who were on boats nearby. The original investigator has passed away. We're reaching out one more time to see if people will come forward with information."

Below, find out what is known so far about one of Hollywood's biggest cold cases, the death of Natalie Wood.

What happened

Wood, who was best known for her roles in "Miracle on 34th Street," "West Side Story" and "Rebel Without a Cause," was 43 when she died on Nov. 29, 1981. The actress went sailing in the family yacht the night before off the coast of California's Catalina Island with her Wagner, now 87, and her "Brainstorm" co-star Christopher Walken. The next morning, Wood was discovered floating face down, although it's unclear exactly how she entered the water.

Accidental death

Wood's drowning was quickly ruled an accident by the coroner. Thomas T. Noguchi said at a news conference days after her death that the actress slipped into the water and drowned while trying to board a small inflatable dinghy tied to the yacht. He said bruises on Wood's left cheek were consistent with injuries she might have sustained if she hit the yacht while falling.

Case reopened

The Los Angeles County Sheriff's Department reopened the investigation into Wood's death in fall 2011. Two years later, her autopsy report was revised to include bruises on her arms and legs that "appeared fresh and could have occurred before she entered the water." The cause of death was also changed from "accident" to "drowning and other undetermined factors."

"The location of the bruises, the multiplicity of the bruises, lack of head trauma, or facial bruising support bruising having occurred prior to entry in the water," chief medical examiner Dr. Lakshmanan Sathyavagiswaran wrote in the report. "Since there are unanswered questions and limited additional evidence available for evaluation, it is opined by this medical examiner that the manner of death should be left as undetermined."

New leads

After the sheriff's department announced it was reopening the case, Corina said they received "more than 100 tips and we followed up on every single one." On Monday, they detailed a new sequence of events of that fateful night, using new witness statements.

"A witness provided details about hearing yelling and crashing sounds coming from the couple’s stateroom," the department's statement from last week said. "Shortly afterward, separate witnesses identified a man and a woman arguing on the back of the boat. The witnesses believed that the voices belonged to Natalie Wood and Robert Wagner.

"As you may recall, Natalie Wood was later reported missing from the boat. The statements from these new witnesses differ from the original version of events as related by previous witnesses, including the individuals on the boat," the statement added.

What the boat captain said

Among those on the boat that night was the yacht's captain, Dennis Davern. In his 2009 book, "Goodbye Natalie, Goodbye Splendour," Davern wrote that Wagner and Wood had an argument while having dinner on the boat in which Wagner broke a wine bottle on the table.

Davern later wrote that Wood left to go to her stateroom afterward, but he heard the two arguing in their room, making him turn up the volume on his radio. He wrote that he later looked outside and saw that Wagner and Wood had come out onto the desk, and appeared to be arguing.

What Christopher Walken said

Walken, Wood's co-star in her last film "Brainstorm," told Playboy magazine in 1997 that only Wood knows what happened that night, as she was alone.

What Robert Wagner said

Wagner reportedly called Wood's death a tragic accident and has publicly expressed support for the new investigation. He has been interviewed by police previously, though not in recent years. Corina said that, in light of the new witness statements, his account no longer "make sense."

"It doesn't add up," he said.

Is there a suspect?

Corina emphasized that right now the department is "not pressing charges on anyone. We're still just trying to figure out what happened."

As for Wagner, he remains a person of interest. The Los Angeles County Sheriff's Department told ABC News last week in a statement, "Wagner has always been a person of interest. This is not new; nothing new to add."

What happened to Wood's children

Natasha Gregson Wagner, Wood's daughter with second husband Richard Gregson, was 11 when her mom died. At the time, it was decided that Wagner, her stepfather, would continue to raise her and younger sister Courtney, who is Wagner's daughter with Wood.

"We were all so shattered by the loss, and we were hanging on to each other," Wagner told People magazine in 2016. "My bond with Natasha is very, very intense. We've hung onto each other through the years and she means the world to me."

He continued: "They'd always been together. So Richard [Gregson], her birth father, and I sat down and came to the conclusion that we felt it was best that Natasha stay with her sisters [including Wagner's daughter with Marion Marshall, Katie] and be raised in the environment that she'd been raised in up to that point -- to the point of Natalie leaving us."

ABC News' Joi-Marie McKenzie, Marilyn Heck, Julie Sone and Alex Stone contributed to this report.