(CNN) -- Questions about bruises on the body of actress Natalie Wood, whose body was found floating off Catalina Island in 1981, led the Los Angeles County coroner's office to change the cause of death from "accidental drowning" to "drowning and other undetermined factors."
"With the presence of fresh bruises in the upper extremities in the right forearm/left wrist area and a small scratch in the anterior neck, this examiner is unable to exclude non-accidental mechanism causing these injuries," wrote Dr. Lakshmanan Sathyavagiswaran, the chief medical examiner.
"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. 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."
Based on a number of factors, including the lack of a life jacket, lack of a suicide note, "this Medical Examiner is unable to exclude non-volitional, unplanned entry into the water," the report says.
"How injury occurred will be listed as found floating in the ocean," it adds. "Circumstances not clearly established."
The change in the cause of death was made public last year, but the report outlining the reasons -- which was dated June 15, 2012 -- was not made public until Monday.
The case is "open and ongoing; nothing definitive has closed it," said Los Angeles County Sheriff's Department spokesman Steve Whitmore.
He said that Wood's widower, actor Robert Wagner, is not a suspect.
A security hold was placed on the report when it came out because of concern "that the frenzy that's surrounding this could contaminate the investigation," Whitmore said.
The hold was lifted last week and the report made public Monday after next of kin were notified.
Homicide investigators decided to take a new look at one of Hollywood's most enduring mysteries in November 2011 after they were contacted by people who said they had additional information about the actress's death, the sheriff's department said last summer.
The announcement persuaded tipsters to come forward with additional "intriguing" information, sheriff's spokesman Whitmore told CNN last January.
Investigators did not comment directly on statements made in news reports in November by Dennis Davern, the captain of a yacht owned by Wood and her husband.
Davern offered a previously unreported account of how Wood's death was reported, saying that Wagner waited hours to call the Coast Guard after Wood went missing off Catalina Island following an argument between the couple.
Wood died on November 29, 1981, off the isthmus of Catalina Island. Dressed in a flannel nightgown, socks and a down jacket, her body was found floating about a mile from the yacht, according to police reports.
The autopsy report showed the 43-year-old actress had two dozen bruises on her body, including a facial abrasion on her left cheek and bruises on her arms.
"My sister was not a swimmer and did not know how to swim, and she would never go to another boat or to shore dressed in a nightgown and socks," said Lana Wood, referring to theories that the actress may have voluntarily jumped from the boat, last year.
Although the county coroner's office ruled at the time that Wood's death was an accident, others said then that that made no sense.
In 2010, Lana Wood told CNN she believed an argument between her sister and Wagner on the yacht's back deck preceded Wood's drowning. She told CNN in 2011 that she did not suspect foul play.
"I just want the truth to come out, the real story," she said.
Davern, the former captain of the yacht Splendour, broke his silence with an account of that day in "Goodbye Natalie, Goodbye Splendour," a book he co-wrote that was published in 2009.
Davern has said he believes Wood's death was a direct result of a fight with Wagner.
In an interview with CNN in 2010, Davern said he believed the investigation was incompetent and suggested there was a cover-up. He said he regretted misleading investigators by keeping quiet at Wagner's request.
Wood and Wagner married in 1957, divorced in 1962, then remarried in 1972. They invited Wood's "Brainstorm" co-star, Christopher Walken, to join them on the Thanksgiving weekend sail that preceded her death.
The Hollywood rumor mill was abuzz with speculation that Wagner was jealous of Walken, but authorities have said Walken witnessed only the events leading up to an argument between the couple.
In his book. "Pieces of My Heart," also published in September 2009, Wagner acknowledged being jealous and having fought with Wood.
After Wagner then argued with Walken and broke a wine bottle, Wood left in disgust and went to her stateroom, Davern told CNN. Walken also retired to a guest room, Davern added, and Wagner followed his wife to their room. A few minutes later, Davern said, he could hear the couple fighting.
Embarrassed, Davern said, he turned up the volume on his stereo. At one point, Davern recalled, he glanced out of the pilot house window and saw Wagner and Wood on the yacht's aft deck. "They'd moved their fight outside ... you could tell from their animated gestures they were still arguing," he said.
A short time later, Wagner, appearing to be distraught, told Davern he couldn't find Wood. Davern searched the boat but couldn't find her. He noticed the rubber dinghy also was missing.
Wagner shrugged and poured them both drinks, Davern said. He suggested his wife had probably gone off in a temper.
Wagner's story, as told in his book, differs from Davern's. He maintains that after the argument with Walken, Wood went to her room and prepared for bed while he and Walken sat on the deck, cooling off.
Wagner writes that he went to check on Wood, but she wasn't there. He maintains that he and Davern searched the boat and noticed the dinghy was missing. Wagner assumed his wife had gone ashore on her own, he wrote.
He radioed the restaurant on shore where they'd had dinner and called the harbor master to see if anyone had seen Wood.
The dinghy was found about a mile from the yacht, and a mile from where Wood's body was found.
Wood's first starring role was as a child in "Miracle on 34th Street" in 1947, and she played alongside some of Hollywood's top leading men -- James Dean in "Rebel Without a Cause" and Warren Beatty in "Splendor in the Grass." She was nominated for Oscars in both of those films, as well as for "Love with the Proper Stranger" (1963), according to IMDb. One of her more memorable roles was as Maria in "West Side Story."
Wagner landed roles in dozens of films in the 1950s and '60s before he hit it big in television. He starred in two series, "It Takes a Thief" (1968-70) and "Hart to Hart" (1979-84), and more recently as Number Two in the "Austin Powers" spy spoofs.
CNN's Kyung Lah contributed to this report.