(CBS News) LOS ANGELES - Natalie Wood's 1981 drowning is no longer being classified as an "accident" on her death certificate.
In a move that comes more than 30 years after the actress' mysterious drowning off Catalina Island, the Los Angeles County Coroner's Office is now re-categorizing her death as "undetermined."
A source who has discussed the case with authorities confirmed to CBS News that the Coroner's Office is changing the official cause of death, and said it is just one step in the continuing probe of the actress' death.
The change in the death certificate was first reported by the website TMZ.
While the Coroner's Office refused comment on the TMZ report and referred questions to the Sheriff's Department, CBS Station KCAL correspondent Bobby Kaple reports that the Sheriff's Department said there is a security hold on the case and will not comment on it, as it as an "open" investigation.
That's, said KCAL legal analyst Steve Meister, means that the probe into Wood's 1981 death has been re-opened, "and it will stay open indefinitely until they can figure out conclusively what happened."
CBS News' "48 Hours" continues to investigate the case, and aired a special report on Wood's drowning late last year that shed new light on the case.
Wood, who was married to actor Robert Wagner, was 43 at the time of her death, while they were on a boat off the California coast.
Wagner speculated that Wood was likely bothered by the sound of their dinghy hitting the side of the boat and went to tie it more securely when she fell overboard.
Meanwhile, Lana Wood insisted her sister was deathly afraid of the water and would never have attempted such a maneuver.
Sheriff's Homicide Detectives reopened the case last year after they say they were contacted by "persons who stated they had additional information about the drowning."
Dennis Davern, the captain of the boat where the couple had stayed, blamed Wagner for Wood's death. He accused Wagner of having a fight with Wood before she went missing and of delaying the search for her after she disappeared.
Wagner's family released a statement last year through a spokesman that said they trusted detectives to evaluate any new information and determine whether it came from "a credible source or sources other than those simply trying to profit from the 30-year anniversary of her tragic death."
During her stellar career Wood received three Academy Award nominations, for "Rebel Without a Cause," "Splendor in the Grass" and "Love with the Proper Stranger." Among her other appearances were the films "The Searchers," "West Side Story," "Inside Daisy Clover," and "Bob & Carol & Ted & Alice." It was during production of the science-fiction thriller "Brainstorm," co-starring Christopher Walken, that Wood died.
Wood and Wagner were married twice, first in 1957 (before divorcing six years later) and then again in 1972. Her death during the Thanksgiving weekend in 1981 has long sparked tabloid speculation that foul play was involved.
Wood, Wagner, Walken and Davern spent time on Thanksgiving weekend 1981 both on Catalina Island and drinking on the yacht.
Wagner has dismissed suggestions that the actress' death was anything more than an accident. In a 2008 autobiography, he recounted drinking with Wood and Walken at a restaurant and on the boat.
Wood went to the master cabin during an argument between the two men, Wagner said. The last time Wagner saw his wife, he wrote, she was fixing her hair at a bathroom vanity and she shut the door.
Despite various theories about what led Wood to the water, he said it was impossible to know what happened.
"Nobody knows," Wagner wrote. "There are only two possibilities; either she was trying to get away from the argument, or she was trying to tie the dinghy. But the bottom line is that nobody knows exactly what happened."
Coroner's officials said at the time that she was "possibly attempting to board the dinghy and had fallen into the water, striking her face."
Wood was found wearing a flannel nightgown, socks and a red down jacket, and Davern identified her body for authorities, according to an autopsy report.
Click below to watch "48 Hours Presents Vanity Fair: Hollywood Scandal."
More on Crimesider