Penny Shtull knows a thing or two about murder and mayhem: stalkers, sex traffickers, serial rapists, mass murderers and other perpetrators of horrific violence. The motives and personalities can differ starkly from one offender to another. Yet when Shtull, a criminal justice professor at Norwich University, studies their crimes, a common theme emerges: Most attackers know their victims, often intimately.

The violent crimes that have made headlines in Vermont in the past year have tended to bear out that theme. They include the deaths of two toddlers in the last three months; the murder-suicide in which Ludwig "Sonny" Schumacher of Essex killed his 14-year-old son, Gunnar, then took his own life; and the 2008 rape and murder of Brooke Bennett by her uncle, Michael Jacques. The killing of Vermont women at the hands of their partners is so common that the state has a committee specifically to analyze those crimes: the Domestic Violence Fatality Review Commission.

Hence, it's no surprise that Shtull, who teaches one of Norwich's most popular classes, "Murder: Our Killing Culture," doesn't devote much time to discussing "stranger danger" with her students, except to note how it distracts the public from the true nature of violence in society. As she points out, the 2011 double murder of Lorraine and Bill Currier of Essex by serial killer Israel Keyes was a tragic but also exceedingly rare event. About the only thing it had in common with most other violent killings in Vermont was that it began in their home.

At first glance, Shtull seems like the least likely person to have become an expert on violent behavior. Soft-spoken and petite, with the innocent good looks of the 1960s "That Girl" star Marlo Thomas, Shtull was raised in a "very functional and loving family." A first-generation Canadian whose parents were both Holocaust survivors, she grew up in a quiet Montréal suburb where she never encountered guns, gangs or drug dealers, she says, or even watched many crime dramas on television. (She still avoids them, including documentaries such as A&E's "The Killer Speaks," on which she recently appeared as an expert criminologist.) In fact, Shtull admits that her first encounter with police occurred when she got stopped for a traffic ticket.

Shtull's family assumed she'd pursue an artistic career, but in college she chanced on a "police technology" program that piqued her curiosity. Though she had no interest in becoming a cop, at McGill University she landed an internship in a forensic psychiatry clinic. There she interviewed sex offenders — and, later, a man in prison who'd stabbed his wife and her lover to death. Shtull, who recalls thinking that the killer "seemed like a nice guy," has been intrigued by the study of violence ever since.

Shtull sat down with Seven Days to discuss criminal patterns, educating young people about the sources of violence, TV versus reality and more.

SEVEN DAYS: You described the murderer you interviewed as "a nice guy." Is it surprising when rapists and murderers seem normal?

PENNY SHTULL: Well, we have to distinguish between a serial rapist or murderer and this guy. I hate to use the term "crime of passion," because "passion" implies something positive, but it was an emotional, albeit violent and brutal crime. I remember sitting across from him, alone in a room. He was a very large guy, and I was just 19 or 20. He had a patch on his eye and flaming red hair and tattoos, like a stereotypical pirate. He said to me, "I killed two people. How do you know I'm not going to kill you?" And I just said, "Well, you asked to talk to someone." He was eventually let out of prison because they assumed he would not repeat [his crime].

SD: Are serial rapists and murderers of a different breed?

PS: There's a different dynamic. Many of those people engage in those crimes while carrying on very regular, daily routines. What makes them successful, in that they can do these crimes serially, is that they come off as nice people. People are not fearful of them. They don't look like people who would harm you. We have this stereotypical image of serial rapists and murderers as people we can spot in a crowd, and they're going to look like Freddy Krueger [from A Nightmare on Elm Street] or whoever that guy was in [The] Silence of the Lambs. Which they don't.

SD: What's the actual likelihood of random violent crimes?

PS: The vast majority of interpersonal crimes are committed between known affiliates. Very few are committed between strangers. It makes sense that we're going to see those crimes in Vermont. We're taught to fear the stranger, whether it's sexual assault or the person lurking in the bushes. We're not taught that it's the person you're studying with, your friend, the person you live with.

SD: How does recognizing that help us educate young people to protect themselves from becoming victims?

PS: In terms of my student body, I'm dealing with 18- to 21-year-olds, primarily males. So, looking at that population, they're more likely to be not only victims but also perpetrators of violence — hopefully not, because most of them are on a good track. It's very different than if we're looking at a middle school class. But even when we talk about child abuse, [kids are] still being taught to be leery of strangers and vigilant of their surroundings when, in fact, it's really your mom, your dad, your coach, your grandparent or your favorite uncle who's more likely to abuse you.

SD: What are your students' biggest misconceptions about violent crime?

PS: Some of the misconceptions they have are the same misconceptions many of us have about crime in terms of the frequency, the dynamics, the nature. Many [students] come in fascinated with law enforcement, but what they know about law enforcement is just what they learned from television. They've been taught that crimes are all solved, that clearance rates are 99.9 percent. But they don't learn much about victims — who they are or the impact crimes have on them. They're very focused on investigations and red lights and sirens. They're somewhat naïve [as] to the true characterization of crimes.

SD: What do you mean by "true characterization"?

PS: Whether we talk about child abuse or murder-suicides or serial killings or mass killings, what is the reality of these crimes versus what we hear in the media? So with child abuse, interpersonal violence, substance abuse — a lot of these crimes and social problems are interrelated. If you see one, you see others. If a child has a parent who's abusing substances, it increases the likelihood that the child will be victimized. It also increases the likelihood that that child will grow up to be a victimizer and/or substance abuser.

SD: What is the clearance rate for violent offenses?

PS: Most people, by watching TV, assume that most murders are cleared, that an arrest was made and the offender put away. But in fact, our clearance rate in 1960 was about 90 percent, but now we're below 65 percent, and in some states it's as low as 30 percent. Some communities don't have the resources — or don't devote the resources — to solving murders. Often it depends on who the victim is. If we have a victim from a college campus, we're going to devote more resources than for a prostitute who gets taken off the street.

SD: So we don't devote as many resources to people who are less visible?

PS: Exactly. And you see it in all these crime shows and who they're focused on. It's often the young, attractive white woman and not necessarily the poor, undocumented worker.

SD: Have the recent high-profile killings involving people who are mentally ill done much to improve the public's general understanding of mental illness?

PS: Actually, when we see these high-profile cases, it often increases people's fear and misconceptions about the mentally ill. One of the things I teach is that mentally ill people are far more likely to harm themselves than they are to hurt other people.

SD: What are the most common predictors of violent crimes?

PS: Of course, we can never entirely predict these things, but the most significant factor would be prior domestic violence. That's what's missed, and often that's not what is talked about in the press.

SD: Does that mean we should be tougher on domestic violence offenders?

PS: Absolutely. I also think it tells us that we need to be more vigilant about domestic violence because they have the potential risk for child abuse, for fatalities, for murder-suicides and for mass murders. But it's not just domestic violence. In some cases, domestic violence is already known to prosecutors and police, but other times it's not. Other risk factors are homicidal or suicidal ideation, where people talk about killing their partner. Access to firearms is another big issue.

Clearly, we live in a state with easy access to weapons — and with a very low crime rate. So it's not as simple as "someone has access to firearms, therefore there will be more crime." But in domestic violence cases, firearms are a very effective tool to threaten someone. Many of these [homicides] are not impulsive crimes; they're planned. One of the things we see in these murder-suicides is when one partner announces that they're leaving. These cases all present us with opportunities to talk about domestic violence, but in general, we don't.

The original print version of this article was headlined "Murder She Taught"