SAN ANGELO, Texas — Using cotton swabs and cameras, lab technicians began taking DNA samples yesterday from hundreds of children and mothers, many in long, pioneer-style dresses, in hopes of sorting out the tangled family relationships within the West Texas polygamist sect.

A judge ordered last week that the genetic material be taken to help determine which children belong to which parents.

Authorities need to figure that out before they begin custody hearings to determine which children may have been abused and need to be permanently removed from the sect compound in Eldorado, and which ones can be safely returned to the fold.

State social workers have complained that over the past few weeks, sect members have offered different names and ages. Also, the children refer to all of their fathers’ wives as their “mothers,” and all men in their families as “uncles.” The testing went on behind closed doors at the crowded coliseum where the children seized in the raid earlier this month on the Fundamentalist Church of Jesus Christ of Latter Day Saints are staying.

The collecting of DNA is likely to take 10 technicians most of the week, and it will be a month or more before the results are available, a spokeswoman for the Texas attorney general’s office, Janiece Rolfe, said.

An FLDS attorney, Rod Parker, acknowledged that family names within the sect can be confusing, but said: “No one is trying to deceive anyone. … It’s not sinister.” Instead, he said that because many of the sect’s marriages are not legal, adults and their children may legally have one name but use another within the community. The April 3 nighttime raid on the 1,700-acre compound probably frightened the children, Ken Driggs, who has studied the sect extensively, said. “If somebody had taken the time to approach them in a way that was respectful, they probably would have gotten the information they needed,” Mr. Driggs said.

The children will be placed in group homes or other quarters until individual custody hearings can be completed by early June. Officials said they will try to keep siblings together when possible, though some polygamous families may have dozens of siblings.

The testing will involve 437 children and possibly hundreds of adults. State authorities revised their count of the children from 416 as they developed better lists and discovered that not all the female members who claimed to be adults were over 18.