Sept. 2, 2011 -- A naked woman found bound and hanged at a California millionaire's historic mansion left a note written in black paint on the door leading to the balcony where she hanged herself, investigators said today.

San Diego County Sheriff Bill Gore would not describe the message painted on the door other than to say it was "not a clear suicide note."

Nevertheless, the starkly written message helped convince investigators that Rebecca Zahau, 32, committed suicide and was not a homicide vicitm.

Zahau was the girlfriend of pharmaceutical mogul Jonah Shacknai. Her death came two days after Shacknai's 6-year-old son Max fell down the stairs at the historic Spreckels Mansion where they were staying. The boy died of his injuries.

Jonah Shacknai released a statement today indicating that he accepts the results of the investigation, saying, "Nothing will ever be the same for our families after these losses, but with today's information providing some much needed answers, we will try to rebuild our lives and honor the memories we carry with us."

Police have concluded that Zahau killed herself after she learned that Max was going to die from his injuries.

"She was obviously distraught," Gore said. "Remember she was the person who found Max."

"Were these deaths the result of criminal conduct? Was Max's death a homicide? The answer is no," Gore told a news conference. "It was a tragic accident. Was Rebecca's death a homicide? Again the answer is no. It was a suicide ... These deaths were not the result of any criminal acts."

Family Rejects Suicide Conclusion at Spreckels Mansion

Zahau's sister, Mary Zahau-Loehner told ABCNews.com today the family will request that police look further into her sister's death and not rush into any conclusions.

"I do not want my sister's death to be ruled a suicide just because you don't have enough evidence to rule a homicide," she said. "Nothing adds up."

She said that her family has hired Seattle attorney Anne Bremner, who said the sheriff's conclusion "doesn't pass the smell test."

Bremner said Zahau never expressed guilt to her family about Max's accident.

The lawyer told ABCNews.com the family said the painted handwriting on the door did not match that of Zahau, who liked to paint as a hobby and had signed her paintings in the past.

Zahau's body was found on the grounds of the mansion in Coronado, Calif., July 13. When police arrived they found her on the back lawn, her hands tied behind her back and her feet bound. Zahau is believed to have died early in the morning that day.

Zahau was found hanging by Shacknai's brother Adam who was staying at the mansion. He told police he cut the body down.

"There's mixed DNA [on the rope] -- it's what they told us," Bremner said. Police told Zahau-Loehner they could not identify that DNA, Bremner said.

On the day that Max fell, Zahau's 13-year-old sister was also at the home. Rebecca Zahau heard a loud noise and found Max at the bottom of the staircase next to a broken chandelier, police said.

Zahau, a former ophthalmic technician, performed CPR on Max and asked her younger sister to call 911, Zahau-Loehner told ABCNews.com today.

Max was hospitalized, but because he had hit his head on the floor "he suffered injury to his upper spinal cord that stopped his heart and lungs. That resulted in brain damage. He subsequently died from that brain injury five days later," said Dr. Jonathan Lucas, who conducted Max's autopsy.

At about 12:50 a.m. on July 13, police say Zahau listened to a message from an unidentified person telling her that Max's condition had taken a turn for the worse. Bremner said that message was from Zahau's boyfriend, Jonah Shacknai.

"We know from our investigation that message left on her phone was to inform Rebecca of Max's grave condition and imminent death," said San Diego County Sgt. Dave Nemeth.

It was at that time that police believe she decided to end her life.

Investigators say she likely found the red rope wrapped around her hands, neck and feet in the garage.

Spreckels Mansion Hanging Was Suicide, Cops Conclude

Police think Zahau painted a message on the bedroom door, cut the rope in sections using the knives found on the floor of the bedroom, and secured the rope to the bed.

"Fingerprints from the guest room entry door jamb, balcony door, large knife and bed leg next to rope were from Rebecca," said Nemeth.

Investigators found the bed pulled away from the wall and the rope extended over the balcony, down into the courtyard.

Police created a video showing how Zahau could have tied her own hands behind her back, using the knots Zahau appears to have used. The knots on Zahau's wrists were not tight, according to Lucas. Police believe she fashioned the rope like a pair of handcuffs, then put her hands behind her back and slipped her wrists into two circles of rope.

"The thinking is, they bind themselves so they won't change their mind midway through," said Lucas.

The slipknots on her feet, wrists and neck were all the same, and the foot impressions on the balcony are consistent with Zahau moving up to the railing, leaning forward and falling over, police said today.

A witness who spoke to Zahau in January told police she had lost weight, seemed stressed and was not exercising.

An undated journal entry on Zahau's phone seems to confirm the same things she had told the witness months before, police said.

But Bremner says that Zahau's family doesn't believe she was depressed in July and suspects she was murdered.

"The family have different people they speculate about, but what they really want is the police to continue their investigation," Bremner said.

Zahau Family Doesn't Accept Investigation Results

Mary Zahau-Loehner, a nurse practitioner who said she spoke to her sister almost every day, told ABCNews.com Zahau had no psychiatric history, and had never taken anti-depressants or attempted suicide.

"Their main reason [for ruling Zahau's death a suicide] is that they did not see any signs of struggle or physical injury that would show there's foul play," Zahau-Loehner said.

Zahau and Shacknai, he 54-year-old multimillionaire founder and CEO of Medicis Pharmaceutical Corporation in Scottsdale, Ariz., had been together for more than two years.

Zahau-Loehner told ABCNews.com that the couple seemed happy together. She had spoken to Zahau the night before she died, and talked about her plans for the following day.

Zahau was "very religious – she did believe if you commit suicide you go to hell," Bremner said. "The case is being prematurely closed."