Since Rebecca Zahau’s bizarre death in tony Coronado two months ago, the rumor mill in the seaside town near San Diego has been churning with theories about what happened to the 32-year-old, who was found hanging nude, her hands and feet bound, from a second-story balcony at the Spreckels mansion.

But at an 11 a.m. press conference Friday attended by experts from the sheriff’s crime lab, county medical examiner’s office, Coronado Police Department, and close to 100 television, print, and radio reporters, the San Diego Sheriff’s Department laid to rest weeks of speculation. The Burmese girlfriend of wealthy pharmaceutical executive Jonah Shacknai committed suicide July 13, they said, because she felt responsible for his son Max’s fatal accident two days before.

“We came to one conclusion that these deaths were not a result of a criminal act,” said San Diego County Sheriff Bill Gore. “Science is our best witness in this case. It is not biased and it doesn’t lie.”

According to police, Zahau bound her own hands and feet with a thick red rope and hanged herself naked off the second-floor balcony of a guest bedroom. She appeared to have secured one section of the rope to the footboard of the bed before she bound her feet, wrapped the rope around her neck, tied her hands behind her back, walked to the balcony, and propelled herself over the railing.

Investigators said they found her fingerprints on a knife that was used to cut the rope in the guest bedroom and on the balcony door, her DNA evidence on the rope and leg of the bed, and her toe impressions on the balcony floor, which looked like her feet were bound before she tumbled over the balcony. Also, toxicology testing indicated there were no drugs or alcohol in her system.

A message Zahau had written in black paint on the door of the guest room was also discovered. Investigators would not comment on the nature of the note or whether it was addressed to anyone.

Investigators concluded that 6-year-old Max Shacknai, who had a history of playing around the stairs, appeared to have stumbled over the second-floor banister and grabbed hold of a chandelier before falling nine feet to the ground below. Police believe Max could have accidentally tripped over a ball or his 14-month old Weimaraner pup.

“No one is suggesting he threw himself over,” said Gore. “We believe he was running down the hall and something caused him to trip, maybe the dog or a ball. That is the best theory we can come up with.”

According to Gore, Zahau was in a nearby bathroom when she heard a loud noise and came out to find Max on the floor at the bottom of the staircase, with broken pieces of the chandelier beside him. There was also a ball and a child’s scooter in the same area.

“The dog was on the first landing when the officers arrived,” added Gore. “He was present around the area where the fall occurred…There was no evidence indicating any foul play. It was a tragic accident.”

No one witnessed the fall, he said. Zahau’s 13-year-old sister, who called 911 at 10:10 a.m., was in another part of the house taking a shower when the tragedy occurred. When paramedics arrived, they discovered that the boy was not breathing and did not have a pulse. Max was rushed to a hospital in Coronado before he was transferred to Rady Children’s Hospital San Diego.

Deputy medical examiner Jonathan Lucas said Max landed on his face and suffered a severe injury to his spinal cord that stopped his heart rate and breathing.

Investigators said that Zahau, who did not go to the hospital, was interviewed after the fall and appeared “obviously distraught.”

Two days later, Shacknai’s younger brother, Adam, called police after discovering Zahau hanging from the mansion balcony at 6:45 a.m. He had flown in from Memphis a few days earlier to be there for his brother. Police said Adam Shacknai climbed onto a table and used a knife to cut Zahau down from the “makeshift noose,” called police, and attempted to resuscitate her. The deputy medical examiner said that the tiny Zahau had been dead for at least two hours before Adam Shacknai found her.

Investigators said that the night before, at 12:50 a.m., Zahau learned from a voicemail message that Max’s condition had deteriorated considerably and that he would most likely die. “The message was to inform Rebecca of Max’s grave condition and imminent death,” said Homicide Sgt. Dave Nemeth. “It was contrary to other reports about Max’s condition.”

“Up to that point his condition was stable,” said Gore. “That changed the dynamic.”

Police said Zahau’s call to her voicemail was the last one she made. The deputy medical examiner said it was likely that Zahau committed suicide within an hour or two of hearing the message. She was alive when she fell over the balcony, said the deputy medical examiner.

“She made the decision to take her own life,” said Nemeth. “She removed her clothing or was already unclothed.”

For nearly two months, police have been trying to determine whether Zahau committed suicide or if something more nefarious was at play. Questions were raised early on about whether Jonah Shacknai, who made his fortune producing acne treatments and Dysport, a competitor of Botox, had anything to do with his girlfriend’s death. Investigators told reporters that Shacknai and his ex-wife Dina Romano, Max’s mother, were at Max’s bedside when Zahau fell from the balcony.

To clarify its findings, the sheriff’s department presented a reenactment videotape showing it was possible that Zahau could have committed suicide and bound her own hands and feet. The videotape showed a woman who appeared to be the same size as Zahau wrapping her wrists with rope, then tying the rope into a knot and placing the rope behind her back.

Gore said the police department shared its findings with the Zahau and Shacknai families. According to news reports, Zahau’s sister, Mary Zahau-Loehner, who lives in Missouri, disputes the findings and does not believe her sister committed suicide. The family has retained a Seattle lawyer to look into Zahau’s death.

“We laid out the case extensively to them in Missouri and answered their questions,” said Gore. “It is unfortunate she can’t accept the results.”

After the press conference, Shacknai issued a statement thanking the sheriff’s department for its “professionalism and dedication in investigating and explaining these terrible events.”

“While the investigation is over, the emptiness and sadness in our hearts will remain forever,” he said. “Max was an extraordinarily loving, happy, talented, and special little boy. He brought joy to everyone who knew him, and we will miss him desperately. Rebecca too was a wonderful and unique person who will always have a special place in my heart. 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.”

According to reports, Zahau, who moved to the United States from Burma 10 years ago, began dating the pharmaceutical mogul about two years ago. Shacknai had divorced Dina Romano, a clinical psychologist, in 2008. He has two children from a previous marriage to a woman named Kimberly James. Zahau quit her job as an ophthalmic technician last December to spend more time with Shacknai and his family.

The couple began spending their summers in Coronado, a city of 26,000 people where Shacknai bought the Spreckels mansion in March 2007.

Investigators said a friend told them that Zahau had lost weight, seemed stressed, and was not sleeping well when she spoke to her last January, months before the tragedy.

“We won’t go into details of her mental state,” said Gore. “There were indications she was unhappy for a while.”