COLUMN ONE : Why Does a Mother Kill Her Child? : The fate of two young brothers in South Carolina has forced Americans to confront painful questions.

“I just hope they were asleep or something and didn’t know the horror of dying alone in that car. I’m just stunned and disappointed in the mother. Evidently they were in the way of what she wanted to do with her life.”

--Alice Valentine neighbor of Susan Smith

For many, the idea is nearly impossible to comprehend.

The deaths of Susan Smith’s two young sons in Union, S.C., and recent cases in San Jacinto, Calif., and Florida, have forced Americans to consider the possibility that a woman might kill her children--then go on national TV to gain public sympathy by blaming someone else.

After nine days of listening to Smith’s story that a carjacker had abducted her sons Michael, 3, and Alexander, 14 months, the nation was shocked to learn Thursday that the 23-year-old mother had reportedly confessed to strapping the boys into car seats and sending her Mazda into a lake.

Only a week earlier, Dora Buenrostro of San Jacinto was arrested on suspicion of stabbing to death her three children, ages 9, 8 and 4, after failing to convince police that her estranged husband had killed them.

And in Florida, Pauline Zile was charged Friday with murder in the death of her 7-year-old daughter, who Zile had earlier claimed had been abducted from a Ft. Lauderdale restroom. After a six-day nationwide search, police said, Zile confessed that her husband had beaten his stepdaughter to death. Walter John Zile has also been charged with murder.

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An estimated 650 to 700 mothers kill their children each year, according to Richard J. Gelles, director of the Family Violence Research Project at the University of Rhode Island.

That represents more than half of the 1,300 children killed by parents or caretakers on average each year since 1976, he said.

Despite these statistics and the recent flurry of publicity, experts say, cases of mothers killing their children have declined in the last century.

Until reliable methods of birth control became widely available, desperate “mothers often felt that this was their only recourse,” said Boston University professor Shari L. Thurer, author of the new book “The Myths of Motherhood.”

More recently, studies have found that mothers who kill their children usually fall into five categories:

They suffer from severe mental illness;

They decide they no longer want their child;

They accidentally batter a child to death;

They want to seek revenge against a spouse;

And, strangely, they sometimes feel a misguided sense of altruism. These mothers either feel they are protecting a child from suffering, or identify with the child in a confused suicide attempt.

“The group we have the easiest time (understanding) have postpartum depression,” said Mark J. Mills, a UCLA forensic psychologist. “They are really psychotic.”

Over the past two decades, about three dozen deaths have been attributed to the illness, a severe mood disorder linked to changing hormones in which stress and fatigue play a major role. It surfaces without warning, usually causing delusions, hallucinations and personality changes.

In a widely publicized case in 1987, Sheryl Lynn Massip of Anaheim at first claimed that her baby had been kidnaped. But she later recanted and was found guilty of murder. The verdict was overturned by a judge who decreed Massip suffered from postpartum psychosis.

Other problems may occur when women suffer from illnesses including schizophrenia or bipolar depression. Sometimes, pregnant women with these conditions may forgo their treatment because drugs such as lithium may put the fetus at risk, experts said.

Some mothers may be healthy but appear to snap under the stress of raising a child without adequate support from family or friends.

“Child rearing is about as demanding a task (as) there is,” Mills said. It “is enormously taxing and challenging. You never have any private time or space. You’re always beleaguered, often tired. It’s a wonder more kids are not battered, beaten, drowned or killed.”

Mothers under extreme stress often give clues--telling others that they feel they will harm their children.

“In the old days, the visiting nurse used to come out and visit every new mom,” said Elissa Benedek, a forensic psychiatrist at the University of Michigan Medical Center. “She was very sensitive about picking up clues.”

But today, without such support systems, some mothers begin to feel incompetent, she said. They feel hopeless, as if they were painted into a corner. This may worsen other problems, including illness or feelings of isolation.

“Many say ‘I am overwhelmed. I can’t take care of this child. I want to protect the child.’ Sometimes they kill them in order to protect them,” Benedek said.

“They have tried to communicate to people how frightened and desperate they are,” she said. “How scared, how worried, how overwhelmed and people don’t listen. It is not a message that anybody wants to hear.”

She said medical students are now taught to pay attention “if there’s a new mom, or any mom, who says she’s worried she’s going to harm her children.”

Sue Myer, director of the Los Angeles-based Childhelp/IOF Child Abuse Hotline, said that counselors often help mothers on the edge. She said they frequently get calls saying, “If you don’t help me stop this child from screaming, I’ll kill him. . . . The sad part is that (a mother) could have called the hot line to get counseling or talk about their feelings.”

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It is the idea of deception that has triggered such outrage in the Smith case, said Charles Ewing, author of the upcoming book, “Fatal Families.”

Women who concoct elaborate ruses to cover their crimes are relying on society’s deep resistance to believing they could be responsible, experts say.

“In many of the cases, the natural response to the overwhelming guilt that you feel (for having done this) is denial,” said Ewing, a professor at State University of New York-Buffalo. “And that denial is immediately reinforced. You get this outpouring of sympathy and support--people saying, ‘They took your babies! Oh, you poor thing!’ ”

Initially, Ewing said, the deception works in her favor. “In the long run, though, once it becomes apparent that she has deceived, then the table turns and you go from being this very sympathetic mother to being the most vile of killers.”

Elizabeth Diane Downs blamed a “bushy-haired stranger” for the shooting death of her 7-year-old daughter and wounding of her two other children on a rural road outside Springfield, Ore., in 1983. But Downs was later convicted in the case after a surviving daughter testified that her mother had shot them.

Prosecutors said she wanted to get rid of her children because they were spoiling her relationship with a boyfriend who did not want to be a father.

Cover-ups can be both helped and hurt by the rise of child advocacy groups, missing children’s networks and intense media interest that can spread a mother’s initial deception wide and fast.

Such attention, as well as advances in law enforcement, can also pick up discrepancies. And authorities have come to be wary of changes in stories or mannerisms.

Downs’ cool behavior at the hospital made authorities first suspect her.

In Florida, Pauline Ziles reportedly referred to her missing daughter in the past tense even before her fate was known.

And last year, Vivian King, 42, of Philadelphia reported that her 17-year-old daughter Shilie Turner was missing. The community rallied around her, raging about the violence in the neighborhood. More than a month later, Turner’s bullet-ridden body was found in a park.

King, who had passed out lavender ribbons in her daughter’s memory, first confessed, later recanted and was eventually convicted of her daughter’s murder.

In the trial, prosecutors pointed out that King was giving away her daughter’s belongings before anyone else knew she was dead.

Some suggest the most implausible tales are manufactured by mothers who harbor an unconscious desire to be caught and punished.

Others point to specific personality traits.

In premeditated crimes such as the Downs’ shootings, there are three elements, said Ann Rule, who wrote a book about the case.

“First, an antisocial personality. Second, histrionics; the actress taking over. Third, you have narcissism. ‘I deserve whatever I want because I’m special.’ Whatever they have to do to get what they want, they will do. And whoever gets hurt, that isn’t really bad because they’re so special.”

Society reserves particular scorn for those who kill and then deceive. “There is a sense that we are going to punish you not only for killing your kids, but for what you did afterward,” said Ewing.

Some suspect the current cases may only feed a growing national cynicism about parents who claim children have been abducted. But according to Ewing, “It may disabuse us of our naive notion that people don’t hurt the people they love. Not only do they hurt the people they love, they also kill them.

“Maybe that is cynicism, but it is also reality.”