NEW YORK Six-year-old Oscar Jimenez Jr. was beaten to death in California, then buried under fertilizer and cement. Two-year-old Devon Shackleford was drowned in an Arizona swimming pool. Jayden Cangro, also 2, died after being thrown across a room in Utah.
In each case, as in many others every year, the alleged or convicted perpetrator had been the boyfriend of the child's mother men thrust into father-like roles which they tragically failed to embrace.
Every family is different. Some single mothers bring men into their lives who lovingly help raise children when the biological father is gone for good.
Nonetheless, many scholars and front-line caseworkers interviewed by The Associated Press see the abusive-boyfriend syndrome as part of a broader trend that deeply worries them. They note an ever-increasing share of America's children grow up in homes without both biological parents, and say the risk of child abuse is markedly higher in the nontraditional family structures.
"This is the dark underbelly of cohabitation," said Brad Wilcox, a University of Virginia sociologist. "Cohabitation has become quite common, and most people think, 'What's the harm?' The harm is we're increasing a pattern of relationships that's not good for children."
Existing U.S. data on child abuse is patchwork, making it hard to track national trends with precision. The latest federal survey on child maltreatment tallies nearly 900,000 abuse incidents reported to state agencies in 2005 but doesn't delve into how abuse rates correlate with parents' marital status or the makeup of a child's household.
Similarly, data on the roughly 1,500 child-abuse fatalities that occur annually in America leaves unanswered questions. Many of those deaths result from parental neglect, rather than overt physical abuse. Of the 500 or so deaths caused by physical abuse, the federal statistics don't specify how many were caused by a stepparent or unmarried partner of the parent.
However, there are many other studies that reinforce the concerns. Among the findings:
• Children living in households with unrelated adults are nearly 50 times as likely to die of inflicted injuries as children living with two biological parents, according to a study of Missouri data published in the journal of the American Academy of Pediatrics in 2005.
• Children living in stepfamilies or with single parents are at higher risk of physical or sexual assault than children living with two biological or adoptive parents, according to several studies co-authored by David Finkelhor, director of the University of New Hampshire's Crimes Against Children Research Center.
• Girls whose parents divorce face significantly higher risk of sexual assault, whether they live with their mother or father, according to research by Robin Wilson, a family law professor at Washington and Lee University.
"All the emphasis on family autonomy and privacy shields the families from investigators, so we don't respond until it's too late," Wilson said.
Census data makes clear that family patterns have changed dramatically in recent decades as cohabitation and single-parenthood became common. Thirty years ago, nearly 80 percent of America's children lived with both parents. Now, only two-thirds of them do. Of all families with children, nearly 29 percent are now one-parent families, up from 17 percent in 1977.
The net result is a sharp increase in households with a statistically greater potential for instability, along with the likelihood that adults and children will reside in them who have no biological connection.
"I've seen many cases of physical and sexual abuse that come up with boyfriends, stepparents," said Eliana Gil, clinical director for the national abuse-prevention group Childhelp.
"It comes down to the fact they don't have a relationship established with these kids," she said. "Their primary interest is really the adult partner, and they may find themselves more irritated when there's a problem with the children."
That was the case with Jayden Cangro.
In July 2006, his mother's boyfriend, Phillip Guymon, hurled the 2-year-old across a room in Murray because he balked at going to bed. The child died as a result.
Jayden's mother, Carly Moore, has undergone therapy since the killing. Yet she continues to second-guess herself about her two-year relationship with Guymon.
"There's so much guilt," she said in a telephone interview. "I never saw him hit my kids, ever. But he was gruff in his manner there were signs that he wasn't the most pleasant person for kids to be around."
Guymon is serving five years in prison for second-degree felony child-abuse homicide. Moore thinks the penalty is too light.
"It's a hard thing," she said, recalling Jayden's death. "You go off to work, you say, 'See you later,' and then everything's completely shattered in a split second."
The slaying of toddler Devon Shackleford was premeditated. Derek Chappell, who was sentenced to death this month, considered Devon an obstacle to an on-again, off-again relationship with the boy's mother and drowned him in an apartment complex swimming pool in Mesa, Ariz.
Such cases trigger a visceral reaction, but there are no simple solutions. Some of the worst cases of child abuse involve biological parents, and examples abound of children thriving in nontraditional households.
"There's no going back to the past," said Washington and Lee's Robin Wilson. "We don't tell people who they can cohabit with. We don't tell them they can't have children out of wedlock."
There are, of course, initiatives aimed at reducing the percentage of children raised by single parents. That's among the goals of the Bush administration's Healthy Marriage Initiative.
"The risk (of abuse) to children outside a two-parent household is greater," said Susan Orr, a child-welfare specialist in the Department of Health and Human Services. "Does that mean all single parents abuse their children? Of course not. But the risk is certainly there, and it's useful to know that."
The federal effort encourages single parents to at least consider marriage. Other programs focus on broadening the support network for single parents. Many social workers say the emphasis should be on nurturing healthy relationships, whether or not the parent is married.
"The primary thing is to have adults around who care about these kids, whatever shape it takes," said Zeinab Chahine, who was a New York City child-protection specialist for 22 years.
Chahine, now with Casey Family Programs, said caseworkers need to learn as much as possible, in a nonconfrontational manner, about the personal dynamics in at-risk households. Is an unmarried partner spending time there? Does that person care about the children or deem them a nuisance?
In the real world, however, learning crucial details about potentially fragile families isn't easy.
"The field struggles with the balance between intrusion in private matters and awareness of significant risks to the child," said Fred Wulczyn of the University of Chicago's Chapin Hall Center for Children. "With a social worker who's in the house on a once-a-month basis, how good do we expect our diagnostics to be?"
The sensitivity of probing into private lives is among many problems underlying the lack of definitive data correlating abuse with parents' marital status and household makeup.
Another problem is inconsistency in the state abuse reports provided to federal agencies. Differing definitions of "household" and varying efforts to ascertain marital status result in a statistical "hodgepodge," according to Elliott Smith, who oversees a national archive of child-abuse research at Cornell University.
Child-welfare specialists hope the statistical gaps will be filled next year by a comprehensive federal survey, the National Incidence Study.
The previous version of the study, released in 1996, concluded that children of single parents had a 77 percent greater risk of being harmed by physical abuse than children living with both parents. The new version will delve deeper into specifics of family structure and cohabitation, according to project director Andrea Sedlak.
Long term, many child-welfare advocates say social changes are needed so day-care options improve and young men in poor communities have job prospects that make marriage seem more feasible.
"These boyfriends increasingly have been raised without fathers and been abused themselves," said Patrick Fagan, a family-policy specialist with the conservative Family Research Council.
Oscar Jimenez Jr., the San Jose, Calif., boy found buried under cement and fertilizer, did have a biological father who was devoted to him. But the father, Oscar Sr., separated from Oscar Jr.'s mother in 2002 and was prevented from seeing his son in the weeks before the boy's death in February, allegedly from a beating by the mother's live-in boyfriend, ex-convict Samuel Corona.
Kathyrn Jimenez, says she, like her son, was abused by Corona, yet she has pleaded guilty to assisting him driving with him from San Jose to Phoenix to hide her son's remains, then keeping quiet about the killing for months.
She was in custody when Oscar Jr.'s funeral took place Sept. 29. She didn't hear the plea of a longtime family friend.
"Listen carefully," Olessia Silva told mourners. "To all the mothers in this world who may find themselves in a difficult situation or harmful relationship: know that there is always, always someone willing to help if you would just reach out."