According to sources, investigators don't have any solid evidence that someone killed Rebecca Zahau, 32, inside a Coronado Mansion in July.
From the beginning, sheriff's investigators were faced with a baffling case.
32 year old Rebecca Zahau, was found naked, hanging by her neck from a balcony at Spreckels Mansion, with her legs and wrists bound by rope, police said.
It appeared to be a homicide from the start of the investigation, but detectives maintained suicide was an option.
Sources, who have knowledge of the investigation, told NBCSanDiego that detectives are reasonably confident that Zahau's death was a suicide.
They said the chain of events began on July 11, 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.
Sources said Zahau felt tremendous guilt over Max's injury because it happened while she was watching the boy. They added that it appears Zahau tied her hands and legs to make sure she didn't save herself.
"I could see a person binding their hands so they wouldn't be able to help themselves trying to get out of the noose once they committed the act of hanging,” said retired homicide detective Rick Carlson. “It really doesn't seem a reason why they would bind their feet."
While it’s unusual for a woman to commit suicide while naked and out in the open, sources said Zahau slept in the nude.
Still, despite the mysterious circumstances, Carlson is confident, investigators will get it right, "I think they're pretty competent investigators and they're going to figure it out."