HELENA -- Neglect and violence experienced in the first 33 months of life can turn an innocent baby into a vicious child killer, Oregon family therapist Robin Karr Morse told an audience of hundreds of Montana social workers Tuesday.

Humans are born with a mere 25 percent of their final brain weight but by age 2, have developed 90 percent of their adult brain mass. The world they experience in the womb and during their first two years of life largely determines their future potential, Morse said.

The Portland therapist pointed to the troubled lives of Dylan Klebold and Eric Harris, who committed the Columbine murders, and other children who have murdered their parents and their peers.

''The roots of violence often begin in the womb and are well rooted by pre-school," Morse told the audience.

Her lecture on childhood violence opened a three-day conference on child abuse prevention being held at Helena's Colonial Red Lion Inn. Through Thursday, speakers from all over the country will talk with more than 400 Montana social workers.

Morse began the conference by leading the audience through research showing that violent tendencies can be planted with babies in the womb. She stressed that emotional development in the first two years of life, replete with cooing and comfort, is necessary for well-adjusted children and healthy human beings.

Cherryl Taylor of Helena, who volunteers with the Court Appointed Special Advocates organization, said Morse's message rings true. Taylor works with seven children who were removed from their homes and said Montana's young moms need to know how their unknowing actions affect their babies.

''Let's get dealing with these young moms," Taylor said after Morse's speech. ''These young mothers don't realize the risks."

Don't blame TV

Violence on television, inappropriate Internet exposure, poverty, access to guns and other social factors play a role in shaping child killers, Morse said. But they are not the only forces driving youth violence, Morse said.

''The cycle begins every day with babies who go home to parents too overwhelmed to cherish their young ones," Morse told the audience.

Parental immaturity, substance abuse, mental illness and other negative factors place infants at risk the moment they are conceived, Morse said. But society waits too long to intervene in their high-risk lives, she added.

''The reality is we wait for highly disruptive signs," Morse said.

Communities generally don't intervene in children's lives until they enter grade school. There, they are identified as the kids who can't sit still, who can't focus, who bite, hit and kick their peers.

They become the aggressive middle school boys who are reactive and impulsive, Morse said. They are the pregnant middle school girls who have ''tuned out" their world.

Later, some turn to violence. Hence Columbine, the Kip Kinkle shootings in Springfield, Ore., and the murder conviction of 13-year-old Nathaniel Abraham in Michigan.

And once children are this far gone, it can be too late to make a difference in their lives, she said.

''When a child can stick a knife in a puppy and lick an ice cream cone at the same time, they are reflecting what they've absorbed," Morse said.

Fast track to jail

Adolescents who never received the infant care they needed may get the government to spend money on them eventually -- in prison.

The United States has the highest proportion of incarcerated citizens anywhere in the world and the prison industry is booming, Morse said. It's the country's third-largest employer behind Wal-Mart and General Motors.

But Morse said the state of Montana could save taxpayer money -- and lives -- if it merely gave moms a helping hand.

''Education begins at zero," Morse said.

Morse said all new moms should be granted free home visits with child care professionals who can show them how to properly nurture their babies. Research shows that high-risk infants who received home visitations from child care professionals were 50 percent less likely to be arrested later in life.

The state of Montana spends $65 a day, or $23,725 per year, on the incarceration of the average, non-violent male offender. Female convicts cost the state $108 per day, or $39,420 per year.

Morse said the state could cut its prison bills by granting moms and babies home visits with professionals, at a cost of $2,500 to $3,000 per infant.

Morse urged social workers to advocate for universal home visits for new mothers as well as high-quality, subsidized child care programs.

''High-quality child care can be a life saver," Morse said. ''It's so much less expensive than what we're doing now."