LOS ANGELES -- Natalie Wood's drowning death nearly 30 years ago came after a night of dinner, drinking and arguments, but the question remains, was it anything more than a tragic accident?

Conflicting versions of what happened on the yacht shared by Wood, her actor-husband Robert Wagner and their friend, actor Christopher Walken, have contributed to the mystery of how Wood died on Thanksgiving weekend in 1981.

Two sheriff's detectives are diving into the mysterious events on the yacht Splendour, although whether they reach any different conclusions than their predecessors did remains to be seen.

They recently received new, seemingly credible information and heard from potential witnesses who weren't included in the original investigation of Wood's death, sheriff's Lt. John Corina said Friday.

But he said nothing has happened to change the official view that Wood's death was an accidental drowning. Wagner is not considered a suspect, he added.

Corina released few details about whom investigators have contacted or plan to re-interview, but the inquiry will certainly lead them to speak with the three survivors of the trip -- Wagner, Walken and skipper Dennis Davern.

Wood's sister, Lana, was not on the boat, but told CNN's Piers Morgan on Friday that she has spoken with Davern many times and believes her sister did not fall off the boat.

"I don't think she fell, I don't know if she was pushed, I don't know whether there was an altercation and it happened accidentally, but she shouldn't have died, and that does stay with me and hurt," Lana Wood said.

"I would prefer to always believe that RJ (Wagner) would never do anything to hurt Natalie and that he loved her dearly, which he did, and I don't believe that whatever went on was deliberate. I've always cared about him. I always will care about him," she said.

The captain said on NBC's "Today" on Friday that Wagner is to blame for the Oscar-nominated actress' death, but didn't offer many specifics.

For years he has maintained that he heard the couple arguing on the boat before Wood went missing and Wagner refusing to immediately search the waters nearby for his wife.

Davern's account is dramatically different from what he told investigators after Wood's body was found in 1981, when no mention of an argument between the couple was made.

Wood was wearing a nightgown, wool socks and red down coat when she was found floating off Santa Catalina Island.

The renewed investigation comes at a time when plenty of attention was sure to be focused on Wood, whose beauty and acting in films such as "West Side Story" and "Rebel Without a Cause" made her Hollywood royalty.

CBS' "48 Hours Mystery" aired a special on the case Saturday.