The death of Rebecca Zahau at millionaire Jonah Shacknai's mansion in Coronado, Calif., in July was a suicide, investigators have said, but the dead woman's sister has said the family is not convinced.

It doesn't add up ... Nothing adds up, said her sister Mary Zahau-Loehner, who was told by the investigators about the findings.

A few days before the death of Rebecca Zahau, also known as Rebecca Nalepa, the pharmaceutical mogul's 6-year-old son, Max, had a fall in the mansion and died a few days after Zahau was found dead.

The 32-year-old Zahau, who was Jonah Shacknai's girlfriend, was found dead in a bizarre fashion at the mansion on July 13. Shacknai's brother, who was staying at the mansion, found her hanging from a second-story balcony. She was nude and her hands and feet were bound with electric wires.
Shacknai was reportedly not at home at the time of the death of his girlfriend, who was of Burmese origin. She had been dating Shacknai for the last two years, and little Max, his son by his ex-wife,  had been under her care when he had the fatal fall.

Deepening the mystery surrounding her death, it emerged that a party had been held at the mansion a day after Max's fatal fall. The following night Zahau died in mysterious surroundings.

Shacknai's brother Adam was staying at a guest house on the property at the time. He reportedly cut the cords to bring Zahau down and attempt to save her life, before calling up police. Emergency crews tried to resuscitate her, but she was later reported dead at the scene.

The San Diego County Sheriff's Department investigators initially said the woman died a violent death and though suicide was a possibility, the circumstances were bizarre.

According to Zahau-Loehner, investigators did not find a suicide note. But they showed her text messages on Zahau's phone from months earlier about issues she had with Shacknai's children, according to the Daily Mail.

More importantly, Zahau-Loehner says she spoke with her sister the night before she died and that she got no hint of anything going wrong with her.

During their talk, Zahau said she would go to a hospital the following morning with clothes for Shacknai, who was there with the child. She also said she would call her parents on the way to hospital.

Too detailed planning for someone who's planning to end their life that night, Zahau-Loehner said.