Sister: Rebecca Zahau's death in Shacknai mansion ruled suicide

(CBS/KFMB) SAN DIEGO - The San Diego County Sheriff's Department detectives who handled the case of Rebecca Zahau, the woman who was found naked hanging from an outside balcony at her boyfriend's San Diego mansion, are saying that she died as a result of her own actions.

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Mary Zahau-Loehner, Zahau's sister, said investigators explained they didn't have enough evidence to suggest otherwise. Evidence of missing items in the home, or signs of struggle or foul play just didn't exists, reports CBS station KFMB.

Sources believe that Zahu's alleged suicide was sparked when Max Shacknai, the 6-year-old son of Zahau's millionaire boyfriend Jonah Shacknai, suffered a severe brain injury after falling from the grand staircase at the mansion on July 11. Max Shacknai died two days after the accident, reports the station.

Zahau felt extremely guilty about the incident, some say, because it happened when she was watching the boy. They also added that it appears she tied her hands and legs to make sure she didn't save herself.

Detectives said Shacknai's brother, Adam Shacknai, was the only other person home at the time of Zahau's death. Adam said he cut down Zahau's body then called 911.

However, Zahau-Loehner does not believe her sister's death was a suicide. She says the way her sister was bound and hanging is a clear sign of an elaborate plan that she could never have come up with. Also, she says her sister would not expose herself for the whole world to see.

"I have thoughts running through my head but there's not evidence pointing yet in anybody's particular direction," Mary Zahau-Loehner says. "And we are not giving up."

Complete Coverage of San Diego mansion death on Crimesider