What Do We Know About Girls Who Kill?

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Photo: Abe Van Dyke/AP/Corbis

It’s a horrible story with a dark, modern twist: Two 12-year-old Wisconsin girls told police that the internet meme Slender Man inspired them to hold a girl down and stab her 19 times. Somehow, she survived. Much of the coverage thus far has, understandably, focused on the bizarre nature of the internet angle. But in doing so, we miss the other factor making this case an outlier, which is that girls — especially those younger than 12 — very rarely try to kill anyone.

What do we know about young girls who kill, and how and why they do it? Science of Us turned to Kathleen M. Heide, a criminologist at the University of South Florida in Tampa, for some answers. Heide has studied juvenile homicidal offenders for more than 30 years, interviewing, she estimates, between 120 and 150 child killers. Here’s what she had to say, based on two papers she recently published, one of which examined 40,000 cases of murders committed by kids ages 6 to 17 years old across the country.

It’s extremely rare for young girls to murder. Heide said that of all juveniles convicted for homicide, only 8 percent are girls. “But when you look at little girls, that’s 12 and under, you’re looking at a very, very small percentage,” Heide said — only about 4 percent of that already small slice of juvenile killers.

But girls are becoming more violent. From 1996 to 2005, arrests for assault increased for girls by 24 percent, according to Heide’s research. But there hasn’t been a similar increase in girls arrested for homicide, Heide said.

Girls who kill are more likely to kill someone they know. Female adolescents who are convicted for homicide are likelier than their male counterparts to have killed someone with whom they have a relationship; boys who kill are more likely to kill strangers, Heide said. Girl killers are also more likely than boy killers to murder family members. 

Most girls who kill do so as a result of a conflict. Heide has found that nearly 80 percent of killings by girls are conflict-related. Murders by boys, on the other hand, are more likely to be crime related — nearly 60 percent of them were directly related to crimes such as robberies.

Most girls who kill don’t use guns. Girls are much more likely to use knives or their own hands or even feet to kill, while boys are more likely to use guns. “I think part of that is because [guns are] more accessible to boys,” Heide said. “Boys tend to grow up thinking more of hunting, or defending themselves. For girls, that’s less likely, though it’s not unheard of. Girls, when they’re involved in conflict-related homicides, will use what’s easily available.”

Girl killers are more likely than boy killers to kill other girls. With boys who kill, Heide says, the victims are about equally likely to be male or female; that’s likely because they’re more often the casualty of a robbery gone awry, or perhaps gang-related violence.

But no matter the child’s gender, Heide says that for as young as the suspects in this case are, it’s important to remember how easily the line between reality and fantasy can become blurred. In many of her interviews with the youngest killers, the kids are almost surprised that the murder actually happened. “It’s sort of, they talked about it, but they never really thought it was going to happen,” Heide said. “It just takes a life of its own.”