Precisely how she was hurt remains a mystery, however.
Wood, 43, died during a yacht trip off Catalina Island with husband Robert Wagner and their friend, actor Christopher Walken. She was initially said to have drowned accidentally while she tried to tie up a dinghy, which was attached to the yacht, but had come loose during the night.
The Los Angeles County Sheriff's Department re-opened the case in November 2011 and the coroner later changed the cause of her death from accidental to drowning and other undetermined factors.
Dr. Lakshmanan Sathyavagiswaran from the coroner's office released a supplemental report Monday, saying he could not verify the injuries the "West Side Story" and "Miracle on 34th Street" actress sustained were caused by falling off a dinghy or attempting to climb back into the boat. The coroner also said she died shortly after entering the water, the Los Angeles Times said.
"The location of the bruises, the multiplicity of the bruises, lack of head trauma, or facial bruising support bruising having occurred prior to the entry into the water," the report said.
"Since there are many 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."
He went on to say he could not rule out "non-volitional, unplanned entry into the water," the Times said.
Wagner has always denied any wrongdoing related to his wife's death.