Smith said the three daughters have been interviewed, but he declined to discuss what they said.

West pleaded guilty in federal court in 2005 to two counts of possessing chemicals intended to be used in manufacturing methamphetamine, according to court records. In August 2006, he was sentenced to 9 years in prison, but appealed three times.

West was released from a federal prison in California in January and transferred to a halfway house in Salt Lake City, said Chris Burke, spokesman for the Federal Bureau of Prisons.

During the Drug Enforcement Administration investigation in 2005, agents stopped by the house, spoke with Huntsman and looked around but it's unknown how extensive the search was.

As he maintained his innocence, Huntsman wrote a letter asking a federal judge to consider leniency at sentencing.

"Darren is a remarkable man, husband, brother, son, son-in-law, friend and father of our three beautiful daughters," she wrote, continuing, "Please we need this guy to keep our family together."

Neighbor Sharon Chipman said the couple married young, and Huntsman never worked except for a short stint at a grocery store.

The three daughters who were living in the house were good young women who have turned out remarkably well considering their father has been in prison, Chipman and Wall said.

West's parents have played an influential role in their upbringing, especially the youngest, who is still in junior high.

Wall said she's puzzled about why Huntsman would have killed the babies, especially considering her youngest daughter, now a young teen, was born during the decade Huntsman told authorities she killed the other babies.

"Why was one of them saved?" Wall said.

Neighbors said they noticed Huntsman's weight fluctuated over the years, with her toggling between baggy and tight clothes, but they didn't realize she was pregnant. Smith declined to say if Huntsman gave birth to the babies in the home or at a hospital.

Cheryl Meyer, a psychology professor at Ohio's Wright State University, said some women who kill their children hide or deny her pregnancy and then dispose of the baby after it's born. Meyer said "concealers" are typically teenagers who do not repeat the act.

"These are usually girls who are 17, get pregnant, become scared to death and don't want to tell their parents," said Meyer, who has written about mothers who kill their children. "They're not 30-year-old women who can go have an abortion."

To combat this, states, including Utah, have safe haven laws that allow women to drop off unwanted newborns to authorities with no questions asked. The mother can remain anonymous as long as the child has not been subject to abuse or neglect.

In coming days, defense attorneys for Huntsman are likely to closely examine her background to search for any evidence of mental illness or a family history that would help explain the alleged killings, said George Parnham, who represented Andrea Yates, the Texas woman who drowned her five children in her bathtub in 2001.

Defense attorneys also will try to determine whether Huntsman sought an abortion and if she told anyone about her pregnancies — all in hopes of understanding actions that otherwise appear incomprehensible, Parnham said.

"You start off with the very nature of what happened. Is there a rational motive?" he said.