(CNN) -- From the time she was an 11-year-old, blue-eyed, freckle-faced blonde until she was a 29-year-old woman with two children, Jaycee Dugard was kept locked away in a backyard compound of sheds and tarps by a couple who police say abducted her.

Jaycee Dugard was locked in a shed tucked under a blue tarp in her alleged captor's backyard.

She was more than 160 miles from home, and her family had no idea where she was.

Nobody else knew she was there except the couple who snatched her off the street in front of her house in South Lake Tahoe, California, in 1991, and took her straight to the soundproof shed, police said.

Dugard's pocket of Phillip and Nancy Garrido's backyard in Antioch, California, was so overgrown no one even knew it existed.

The details about Dugard's time in captivity emerged Thursday after one of Northern California's most enduring mysteries was solved and the Garridos were arrested and accused of her kidnapping.

Anyone who came across the couple's backyard, littered with garbage cans and a dishwasher, would assume that it ended at a 6-foot fence. Watch aerial images of the backyard compound »

"You could walk through the backyard and never know there was another set of living circumstances," said Fred Kollar, undersheriff of El Dorado County. "There was nothing that would cause you to question it. You can't see it from either adjoining property. It was presumably well arranged."

But tucked away beyond the tangle of bushes, high grass and trees was a blue tarp that concealed the only world Dugard had known since her abduction.

Kollar said the property had "a hidden backyard within a backyard." It included several sheds no taller than 6 feet, two tents and several outbuildings, "where Jaycee and the girls spent most of their lives."

It also held a vehicle that matched the description of the car used in Dugard's kidnapping, Kollar said.

The "secondary" backyard was inside the first and was "screened from view." One of the sheds was soundproof, he said.

In it were sheds and tarps, a makeshift bathroom and shower, along with electricity supplied by extension cords. Kollar compared the primitive conditions to camping.

Dugard lived for several years there by herself. The sheds were locked from the outside.

She grew up and had her captor's children there, and raised them there.

"None of them have ever been to school, they've never been to a doctor," Kollar said. "They were kept in complete isolation in this compound, if you will, at the rear of the house," he said. "They were born there."

The children, both girls, are now 15 and 11.

"They are all in good health," Kollar said in response to a question about how Dugard and her children are doing. "But living in a backyard for the last 18 years does take its toll."

All About Missing Children • California