The entertainment news Web site TMZ reported Friday its law enforcement sources say the Los Angeles County coroner filed documents making the change late last month and members of Wood's family told it county sheriff's deputies paid them a visit to inform them of the change.
Sheriff's investigators have reopened the investigation into the death of Wood, who was 43 and married to actor Robert Wagner when she fell off a boat anchored off Catalina Island in November 1981 and drowned, TMZ said. There had been a party aboard the boat earlier. Actor Christopher Walken also was on the boat that night.
The relatives said detectives told them the change was made, in part, because some of the bruises on Wood's body were inconsistent with death by drowning, TMZ said. The family members also said authorities can't prove definitively whether Wood died accidentally or was the victim of foul play, though they were told she definitely drowned.
CBS News reported Saturday it had confirmed the reclassification of the death certificate.
Wagner has speculated Wood may have been bothered by the sound of their dinghy bumping the side of the boat and went to tie it more securely when she fell overboard.
Lana Wood has said her sister had a fear of the water and would not have tried to adjust the dinghy herself.
Sheriff's investigators said they reopened the case last year after being contacted by "persons who stated they had additional information about the drowning," CBS reported.
Dennis Davern, who piloted the boat where the couple had stayed, blamed Wagner for Wood's death, saying the couple had fought before she disappeared and that Wagner had delayed the search for her.