Police missed an opportunity to free Jaycee Lee Dugard in 2006 when they were called to the home where she was allegedly held for 18 years but failed to find her, a spokesman said tonight.
Ms Dugard had been missing since she was snatched off a street by two people in a grey car while walking to a bus stop near her home in South Lake Tahoe, east of San Francisco, on June 10th, 1991.
She spent 18 years living in sheds and tents behind the home of her accused abductor, a convicted rapist who fathered two children with her, police said.
It has been reported the woman recently walked into Concord police station in California.
Ms Dugard, now 29, was found after a parole officer for her accused kidnapper became suspicious, leading to a search of his home near the town of Antioch, about 160 km southwest of where she was abducted.
Police say the search turned up a hidden "backyard within a backyard" at the home of registered sex offender and convicted rapist Phillip Craig Garrido, where Ms Dugard and the two children were confined in a series of sheds and tents.
Authorities said Garrido (58) was suspected of fathering two children with Ms Dugard, girls now aged 11 and 15. Garrido and his wife Nancy (54) are being detained on suspicion of kidnapping.
Sheriff Warren Rupf said officers were called to the home of Garrido three years ago after reports people were living in his back garden.
He added: “On November 30, 2006, we missed an opportunity to bring earlier closure to this situation.
“A caller to our 911 dispatch offered that there were tents in the neighbour’s backyard, that people were living in them, and that there were young children.
“The caller also said that Garrido was psychotic and had a sexual addiction.” He said officers went to Garrido’s home but did not go inside and said they found no evidence “of criminal behaviour”.
He apologised for what he described as “not an acceptable outcome”. He added: “We should have been more inquisitive, more curious and turned over a rock or two.”
Earlier, El Dorado County Undersheriff Fred Kollar told a news conference: "She was in good health but living in a backyard for 18 years must take its toll".
"None of the children had ever been to school, none had been to a doctor. They were kept in complete isolation in this compound," Mr Kollar said.
Carl Probyn, Ms Dugard's stepfather, said on television he and her mother "cried for about 10 minutes" after they were told by authorities that she had been found alive.
Garrido and his wife Nancy Garrido were arrested over Ms Dugard's abduction and prosecutors said they were likely to be charged today.
In a telephone interview with a local radion station, Garrido urged people to wait for more details about what took place at the house.
"You are going to be completely impressed," he said. "It's a disgusting thing that took place with me at the beginning. But I turned my life completely around and to be able to understand that, you have to start there."
While the case of Ms Dugard's abduction had remained open for the past 18 years, police had never found a trace of the missing girl or the grey car until Tuesday, when Garrido tried to enter the University of California, Berkeley campus with the two girls to pass out religious leaflets.
A campus police officer found his interaction with the girls suspicious and investigated his background, ultimately alerting his parole officer.
During a visit with the parole officer, Garrido brought his wife, the two girls and a woman identified as "Allissa" - who proved to be Ms Dugard.
Authorities said Garrido had served time in a Nevada prison for a 1971 kidnapping and rape conviction.
The San Francisco Chroniclenewspaper reported Garrido was described as strange by his neighbours, who said he conducted religious revivals in a tent and claimed to have invented a device to control sound with his mind.
Asked by reporters why the parole officer, who had visited Garrido's home, had never found Ms Dugard or the secret backyard compound, authorities said it was well hidden behind a fence, vegetation and a tarpaulin.
Reuters