SAN ANGELO, Texas - For nearly two months, Texas child-welfare officials had insisted that conditions at a polygamist group's ranch were so abusive that none of its members should be allowed to keep their children.

Now, however, one of the largest custody cases in U.S. history is unraveling, and some are looking for what went wrong when the state raided the Yearning for Zion Ranch and removed more than 400 children.

Since the state Supreme Court ruled Thursday that the Texas Department of Child Protective Services overreached when it swept the children into foster care, agency officials have been unwilling to discuss the case, their strategy, or what went wrong.

However, some close to the debacle say the operation was doomed from the start by a series of missteps.

First is the oddity of a religious sect the agency knew little about, exacerbating the inherent perils of balancing parents' rights and child safety. Then there were the abuse allegations, starting with a mysterious telephone call and echoed by disgruntled former members, seemingly accepted at face value.

And an ill-fated 1992 brush with another religious sect - which led to the fiery deaths of 21 children at the Branch Davidian compound near Waco - lingers on the agency's collective conscience.

"It's difficult to know whether, in fact, they screwed it up," said Linda Spears, vice president of the Child Welfare League of America, a national collection of nonprofits that aid abused and neglected children. "It's the 20/20 hindsight thing."

Folks in Schleicher County, a dusty patch near the middle of Texas, had been at least curious, if not suspicious, of members of the Fundamentalist Church of Jesus Christ of Latter Day Saints, a Mormon breakaway group whose members believe that polygamy earns glorification in heaven.

Members of the group revered leader Warren Jeffs as a prophet. Since the start of the group's Texas ranch, he has been convicted in Utah as an accomplice to rape and is in jail in Arizona awaiting trial on separate charges.

Sheriff David Doran cultivated a confidential informant to monitor the group's activities, and former FLDS members recounted abuse and forced marriages to anyone who would listen.

Investigators "listened to a lot of misinformation and allowed themselves to be kind of captivated by these anti-FLDS people," said FLDS spokesman Rod Parker.

When someone purporting to be a pregnant 16-year-old called a hotline claiming her middle-aged husband had beaten her, authorities went in with Child Protective Services workers on April 3. But the call may have been a hoax.

"We had no choice but to treat those calls as credible," said Tela Mange of the Department of Public Safety, which is still investigating possible sex abuse at the ranch. "If we had not treated them as credible and something bad happened, people would be very upset,"

Children and mothers were taken from the ranch because CPS workers thought it would be better to interview them at a neutral location, something that wasn't done in the Branch Davidian situation.

CPS workers were confused about names, ages, and relationships of the children and adults in the complicated FLDS group marriages. The agency said then that it believed sect members were misleading investigators about the names, ages and parentage of the children.

Although caseworkers said when they took custody of all the children that the sect was forcing underage girls into marriage and sex, and training boys to be adult perpetrators, only a few dozen of the children turned out to be teenage girls, and only a handful had children or were pregnant. Of 31 mothers CPS said were minors, at least half turned out to be adults.

Spears said that despite the high-profile nature of the case, "at the time you walk in, you have very little information even in the best cases," noting the snap risk assessments that caseworkers are often asked to make.

She said, "There's no exact science being practiced here."