A woman found hanged, bound and nude at the estate of a prominent pharmaceutical executive in July -- two days after the fatal fall of the executive's young son -- committed suicide, police said on Friday.

San Diego County Sheriff Bill Gore said investigators had ruled out foul play in the death of Rebecca Zahau, 32, who was found dead on July 13, dangling by her neck from a courtyard balcony at the landmark Spreckels Mansion in Coronado, an upscale island beach resort near San Diego.

She was living there at the time as the girlfriend of Jonah Shacknai, 54, the founder and chief executive officer of Medicis Pharmaceutical Corp, the Arizona-based maker of the acne treatment Solodyn and wrinkle-filler Restylane.

The unusual death came two days after Shacknai's 6-year-old son Max was critically injured in a fall from a staircase while being looked after by Zahau at the home. The boy died six days later in what investigators have ruled an accident.

These deaths were not the result of any criminal act, Gore told reporters at a news conference to announce the conclusion of a seven-week investigation.

Shacknai and his brother, Adam, a guest at the estate who found Zahau's body and called police, and the executive's ex-wife, Dina, whom he divorced in January, all fully cooperated with investigators and were never considered suspects, Gore said.

The sheriff said Zahau had left a message scrawled in black paint on the inside door to the bedroom leading to the balcony, but he did not reveal what it said, nor did he detail why investigators believe she took her own life.

But he suggested that Max's accident may have contributed to her state of mind.

There were indications she had been unhappy for a while, he said. We know she got a voice message (a few hours before her death) where she learned that Max's condition had deteriorated.

He said there were no signs of a struggle, sexual assault or drugs in her system, and no indication that Zahau was incapacitated in any way before she loosely tied her own hands and feet, slipped her neck through a long noose that was anchored to the bed, then threw herself off the balcony.

He said an autopsy showed she died of asphyxiation and that injuries to her neck were consistent with a 9-foot drop, the distance she fell before the rope was fully extended. Investigators found only Zahau's DNA on the red-colored rope.

Relatives of Zahau, who was from Paradise Valley, Arizona, and was herself divorced in February, have said they do not believe she took her own life.

Some members of the Zahau family have said they are not satisfied with our conclusion, and they may conduct their own investigation, Gore said.

Police have said Zahau was the only adult home at the time that Shacknai's son was running through an upstairs hallway and tripped, falling head-first down the staircase on July 11.

Gore said the boy landed on his face and snapped his neck, injuring his spinal cord and causing him to stop breathing, leading to irreparable brain damage.