AUGUSTA — Cold-blooded murderers such as John Wilkes Booth, Jeffrey Dahmer, David “Son of Sam” Berkowitz and the Boston Strangler have more in common than just their savagery. All of them, it turns out, abused animals when they were young.

Serious and repeated acts of animal cruelty are a common thread in the childhood and adolescent histories of many violent offenders, according to Dr. Randall Lockwood of the Humane Society of the United States, who spoke Wednesday during a Kennebec Valley Humane Society seminar on the link between animal abuse and violence against people.

Long before they committed the crimes that made them notorious, Booth strangled cats, Dahmer poured motor oil into a tank of fish, Berkowitz killed his grandmother’s parrot and his neighbor’s dog, and strangler Albert DeSalvo shot arrows at small animals, according to Lockwood.

“They all did things which made them feel stronger or more competent, and no one said anything, nobody set any limits,” he said, adding that anthropologist Margaret Mead preached that one of the most dangerous things to happen to a child is to kill or torture an animal and get away with it.

Animal cruelty coupled with fire setting, truancy and assault are the earliest warning signs of at-risk youth, according to Lockwood, who said research shows consistent patterns of animal abuse among perpetrators of child, spousal and elder abuse.

There were 520 valid complaints of animal cruelty in Maine in 1997, according to the Animal Welfare Program in Augusta. None of the incidents involved children.

About 70 representatives of mental health agencies, domestic violence projects and animal control departments listened intently Wednesday as Lockwood, an expert in animal behavior and the cycle of abuse, offered more examples of the connection between hurting animals and hurting people.

The link is evident even in the recent spate of school violence, he said. For example, Luke Woodham, who went on a shooting rampage in Pearl, Miss., wrote in his diary that he laughed while he killed “my dear dog Sparkle.” Baby-faced Andrew Golden, who shot his classmates in Jonesboro, Ark., would shoot songbirds in his yard. And Kip Kinkel of Springfield, Ore., who killed his parents and fatally shot two classmates, was known to “torture animals and then tell us about it,” according to a friend.

The connection between animal abuse and violence against people was largely ignored until the late 1960s and ’70s, said Lockwood, when the FBI recognized that 25 to 50 percent of offenders had an early history of animal cruelty that had gone unreported and undetected.

Now, the FBI identifies animal cruelty as one of a cluster of juvenile behaviors associated with increasingly violent behavior, and even uses animal cruelty in analyzing the threat potential of suspected criminals, Lockwood said.

Later, Sandi Hodge, director of child welfare for the Maine Department of Human Services, told the group that animals could offer a way to break the cycle of violence for children.

“They can be part of the healing process,” said the social worker. “They can be an amazing bridge, a first step for kids learning to empathize and to care and nurture.”

Hodge recalled a dog sled trip to the Allagash five years ago in which a young Maine boy who had been horribly abused began drawing pictures of the dogs and, later, of himself and his own experiences.

“It was the first time he ever honestly talked about his abuse, the first time he confronted the horror he had endured for 10 years,” Hodge recalled. “It was a real breakthrough.”

Some of the kids on the trip had abused animals, Hodge said, but “we watched them and that’s not where they were. They connected in a positive way, and my guess is that those kids will never abuse animals again.”

Meanwhile, Deb Clark, executive director of the Kennebec Valley Humane Society, hoped the seminar would induce people to look at animal abuse differently.

“Those who work in animal welfare are frustrated because people don’t take animal abuse seriously, and because so many animal abuse cases don’t make it to trial since people don’t come forward,” she said. “Too often, we hear anonymously about an incident. But maybe if more people are aware of the link, they’ll take it more seriously and intervention can take place.”

In fact, the seminar already has made a difference. Hodge said later that after listening to Lockwood, she has decided to begin compiling the data on the instances of animal abuse for children coming through DHS. Although the information is indicated in each child’s records, the numbers have not been available in one place.

She also will begin cross-referencing the numbers with animal control officers. “This could point out some things we can do better together, and help us have a better handle on the extent of the problem so we can revise interventions,” she said.