The couple accused of kidnapping an 11-year-old girl and keeping her hidden in their backyard for 18 years pleaded not guilty to dozens of charges on Friday as police searched their home for evidence related to murders of prostitutes in the 1990s.

Phillip Garrido, 58, and his wife, Nancy, appeared in El Dorado County Superior Court to answer 29 criminal counts that included kidnapping for sexual purposes, forcible lewd acts on a child and rape.

Neither spoke in court and their pleas were entered by their attorneys. Garrido, a convicted rapist who served time in prison, showed no emotion. But his wife kept her head down and cried in the packed courtroom.

Meanwhile, police apologized for failing to follow up an anonymous tip in 2006 that could have led them to Jaycee Dugard, who was snatched from a bus stop near her South Lake Tahoe home in 1991.

Authorities believe that the now 29-year-old Dugard spent most of the past two decades living in squalid tents and sheds in Garrido's backyard. He is accused of fathering two children with her.

On Friday police searched Garrido's home in the San Francisco Bay Area suburb of Antioch for evidence that might also connect him to killings of prostitutes in the 1990s. Some 10 prostitutes were killed in the industrial area near where Garrido worked at the time, the San Francisco Chronicle reported.

Contra Costa Sheriff Warren Rupf acknowledged that a neighbor of Garrido called police in 2006 and said he was a psychotic with sexual addictions and had children living in tents in his backyard.

'NOT AN ACCEPTABLE OUTCOME'

When an officer went to the home he spoke with Garrido in the front yard, but did not enter the property, Rupf said, adding that the officer was not even aware Garrido was a registered sex offender, even though he is listed as such on a public database.

This is not an acceptable outcome, Rupf said. Organizationally we should have been more inquisitive or curious and turned over a rock or two.

The case evokes the 2002 kidnapping of Elizabeth Smart, a teen-ager abducted at knifepoint from her Salt Lake City bedroom by a drifter and self-styled prophet and his wife.

Smart lived with the couple for nine months, part of that time at a campsite hidden in the hills above her family's home.

Last year an Austrian man was arrested for keeping his daughter in his basement and fathering seven children with her.

Garrido's brother told the San Francisco Chronicle that Garrido was mentally unstable with a history of drug abuse and described his sister-in-law as a robot under his control.

Garrido, who boasts of his ability to speak in the tongue of angels on a blog called Voices Revealed, gave an interview from jail to Sacramento radio station KCRA.

You are really going to be surprised what happened was a powerful, heart-warming story, he said. You are going to be absolutely impressed with this disgusting thing that took place with me in the beginning. I turned my life completely around.

Authorities say Garrido kept Dugard and the two daughters he fathered with her in the backyard of the home he shared with his wife. The yard was surrounded by tarps and tall trees, making it difficult for outsiders to see inside, they say.

Dugard was found this week after she showed up with Garrido for a meeting with his parole officer. Her appearance and that of her 11- and 15-year-old daughters, all of whom the parole officer had never before met, caused suspicion and Garrido was arrested soon afterwards.

Suspicions first arose the day before, when Garrido was seen on the campus of University of California at Berkeley passing out leaflets with the two children.