That's according to researcher and speaker Phil Chalmers, who has interviewed more than 200 teens who look just like their peers, yet each has caused the death of another human being.
Chalmers was one of three presenters at a recent two-day seminar for law enforcement and educators that focused on teen killers, school shootings and preparedness.
Teen murders peaked in 1993, when 3,800 juveniles were arrested for homicide. Today, about 1,800 teens kill every year, said Chalmers, noting the trend is not new. The first teen murder recorded dates to 1786, when a 12-year-old Connecticut girl killed a 6-year-old by strangling and beating her with a rock. The deadly assault was triggered by a dispute over strawberries.
The youngest shooter, who shot and wounded his 18-year-old babysitter for stepping on his foot, was 4 years old. Police were so incredulous the child could have committed the offense, despite his confession, they returned the gun to him to test his knowledge of loading the weapon. They were shocked the boy was able to do so.
The top triggers for teen homicide are suspension, expulsion or arrest, said Chalmers, encouraging educators to seek aid from law enforcement when disciplining students.
The first school shooting occurred in 1956, said Chalmers. The first fatal school shooting happened 10 years later.
The first female school shooter opened fire on an elementary school across the street from her San Diego home. She killed two and injured nine. When asked about her motive, the girl answered, "I hate Mondays."
Like many other teen shooters, the girl's father armed her when he gave the gun to her as a Christmas present.
The deadliest school shooting in the United States was in 1999, when two students plotted and carried out a massacre at their high school in Littleton, Colo. Thirteen died and 23 were wounded in the attack on Columbine High School.
"School shooters are no different than terrorists," said Chalmers, noting the two killers planned the attack for 18 months. It would have been much more devastating had they been able to carry out their intent to detonate a bomb in the crowded cafeteria.
Statistics aside, Chalmers said, it's important to realize the phenomenon is nothing new, teen killers are getting younger every day and "they don't look like killers."
There are six types of teen killers, according to Chalmers.
There are family killers, who murder family members, and school shooters. Gang/cult killers are motivated by an outside group. Crime killers commit murder secondary to another crime, such as burglary or rape. Baby killers take the lives of newborns and thrill killers kill just "to feel what it feels like," Chalmers said.
Chalmers also has identified 10 causes of teen murder.
A 16-year-old from Minnesota was mentally ill and suicidal when his mother made him run errands for her and his dad assigned him the chores of shoveling snow and chopping wood. Motivated by a fight with his father over a record, the boy took up the ax he'd used to chop the wood and slaughtered his mother, father, brother and sister.
Some teens, without spiritual guidance and proper discipline, feel they have nothing to live for and nothing to lose.
"Prison to a lot of kids is good," said Chalmers, noting a bed, regular meals and health care is more than they may get outside custody.
Others are fascinated with the criminal lifestyle, as was the case with two New Hampshire teens who under the guise of taking a survey, entered the home of a couple who they killed by stabbing and cutting their throats.
Peer pressure motivates some, while others are nudged into killing through a fascination with guns, bombs and knives. An Oregon teen killer, following a suspension from school, used weapons purchased for him by his father to kill his parents. Returning to his high school, he shot several students, killing two and injuring 22.
"Innocent kids are victims because the shooter was bullied by other students," said Chalmers of the 15-year-old's 1988 shooting spree.
An Ohio boy had turned to Satanism and set up an altar in his bedroom before killing his parents. He decapitated his father and, short of the strength to lift her onto nails bored into the wall, killed, but failed to crucify his mother. The teen, who initially wanted to be a priest, was determined to break all 10 commandments.
Substance abuse causes others to murder. A Tennessee boy shot and killed his principal with a gun he'd taken to school as trade for prescription drugs.
"We need to tell schools what to do," said Chalmers.
Anger, depression and suicidal tendencies are a great motivator, according to Chalmers, who said, "Every homicide is subconsciously suicide and every homicide is, in a sense, a psychological killing." Awareness to the signs of suicide -- talk about a plan, giving away prized possessions, risky behavior -- can help to prevent both suicide and homicide, he said.
Media is the catalyst that throws some over the edge, said Chalmers, who said increasingly violent media, video games and music gives kids ideas. A 14-year-old quoted a line from a Stephen King book after killing his algebra teacher and two students at his Moose Lake, Wash., high school.
"We need to tell schools what to do," said Chalmers, referencing the case of the Tennessee case that was facilitated by a teacher who, after hearing rumors the boy was armed with a gun, sent him to the office.
"We need to be the protectors of our kids," Chalmers said. "Many victims come from families that are naive."
The top causes for teen murder are an unstable family life or school bullying.
It is with the face of a 16-year-old Pearl, Miss., teen that Chalmers paints the picture of a victim-turned-killer.
Yelling, "This ends now," the boy, after beating his mother to death, entered his school with a gun and started shooting.
"I guess the world's gonna remember me now. I'm gonna get pretty famous," the boy said.
In retrospect, he, as many others, say they were seeking attention and had demonstrated previous warning signs that, if identified, could have prevented mass murder, according to Chalmers, who said cruelty to animals, a fascination with setting fires and bedwetting into adolescence are behaviors that can warn of future homicide.
Warning signs of violence also include threats of harm, violent or threatening schoolwork or artwork, a fascination with deadly weapons, obsession with violent media, journaling or blogging about thoughts, threats and plans, showing a fascination with other school shootings or violent books, the commission of petty crimes, dressing the part of a school shooter, self-abuse and implementing a drastic change in appearance.
"Keep your eyes open," Chalmers said, noting by pulling a seemingly troubled teen aside to talk may be all it takes to derail a mass murderer's plan.