California- from www.news.com.au – POLICE are investigating accused sex slave abductor Phillip Garrido over the murders of several prostitutes.

Yesterday officers sealed off his house and began searching the secret backyard compound for clues linked to the killings as details emerged of the convicted sex offender’s bizarre and brutal life.

“Pittsburgh police yesterday sealed off the house in Antioch to investigate potential connection between a series of murders of prostitutes in the Bay Area in the early 1990s,” Contra Costa County Sheriff’s Captain Daniel Terry said.

Garrido, 58, had worked near the site where the murdered women’s bodies were found.

He and wife Nancy, 54, yesterday pleaded not guilty to 28 charges linked to the 1991 abduction of 11-year-old Jaycee Lee Dugard, whom they allegedly held captive in their backyard for 18 years. She gave birth to Garrido’s two daughters, now aged 11 and 15.

The Garridos each face six charges of rape, seven counts of committing lewd acts upon a child, two counts each of kidnapping and one count each of false imprisonment.

Wearing an orange, prison-issue jumpsuit, Garrido looked gaunt as he stood shackled in the dock at the El Dorado County Superior Court in Placerville, California.

Neither he nor his wife spoke during the five-minute hearing. They face life in prison.

Their alleged crimes came unstuck this week when Garrido took Ms Dugard, now 29, and his daughters to a meeting with his parole officer.

Police yesterday admitted they had botched their efforts to find her sooner, failing to properly investigate an anonymous tip-off in 2006.

A 911 caller had said young girls appeared to be living in sheds in Garrido’s backyard, but the attending officer failed to check beyond the front yard.

“We may have missed an opportunity to have intervened earlier,” Sheriff Warren Rupf said yesterday.

The backyard of Garrido’s house had been separated into three parts. The rear two are believed to be where Ms Dugard and her daughters were kept in a collection of tents and structures.

In one tent yesterday, a bouquet of yellow flowers were visible and in front of another, federal agents had layed out a pair of pink pyjama bottoms.

The yard had several ragged lawn chairs, an empty plastic pool, swings, a trampoline, couch and the dusty old car police allege Garrido used to abuct the girl 18 years ago from a bus stop. The car was not visible from the road.

Garrido’s family has condemned his as a “fruitcake” and a “crazy person” who went off the rails after he got hooked on LSD as a teenager. They said he was religious fanatic who controlled Nancy, whom he met and married while he was in jail for kidnapping a 25-year-old woman and raping her in an abandoned warehouse in 1976.

Garrido’s older brother, Ron, described Nancy, who had been visiting an inmate when they met, as a “robot”.

“I know my brother, and I can believe he did that . . . he’s a fruitcake,” Mr Garrido said.

Garrido’s father, Manuel, said his son had been a model youth who played guitar in a band, helped with household chores and loved to crack jokes.

“Everyone loved him, but his character took a turn for the worse when he discovered drugs,” he said.

“After he got the LSD pills, he was gone. It ruined his life. He did a lot of crazy things after that.”

Garrido served 11 years in jail for the kidnapping and rape of a woman in the South Lake Tahoe area in 1976.

He forced her into a car, bound and gagged her, then drove her to the crime scene — a deserted warehouse furnished with adult magazines, sex toys, wine, hot water and a spotlight.

In a bizarre twist, Garrido has claimed on his internet site in a string of unnerving and incoherent posts that he had the God-given power to control sounds with his mind.

“The Creator has given me the ability to speak in the tongue of angels in order to provide a wake-up call that will in time include the salvation of the entire world,” he said in the final entry, dated August 14.

The blog has drawn hundreds of angry, profane and obscene denunciations since the revelations of the abduction of Ms Dugard.

In an interview with a local TV station, Garrido acknowledged his abduction of Ms Dugard from outside her South Lake Tahoe home in 1991 had been a “disgusting thing”.