Some say it's due to tougher economic conditions and easy access to guns. Others say it reflects a shift in television programs to more impersonal violence. Whatever is fueling it, violence among strangers appears to be on the rise.
For years many Americans took some comfort in the statistics that most murders committed in the United States were between people who knew each other -- even if only slightly. It seemed to signify that if one could avoid confrontation with those one knew, he or she could control the situation and stay out of trouble.
But an increasing proportion of murders reported to police involve people who do not know each other. And a consistently high share of other violent crimes reported involve strangers.
Between 1980 and 1984 the percentage of murders committed by strangers and reported to police increased from 13.3 to 17.6 percent, according to the Federal Bureau of Investigation's (FBI) Uniform Crime Reports.
Southern Illinois University criminologist Marc Riedel, who has studied detailed police records in a number of cities and is writing a book on the subject, suggests the actual figure is 20 to 30 percent. When police don't know if the victim knew his assailant or not, Dr. Riedel explains, they classify the relationship as ``unknown.'' (In 1984 some 26 percent of all murders fell in that category.) When such cases are solved by police, they rarely amend the relationship category in reports to the FBI.
Riedel says the proportion of murder cases not cleared has been increasing over the last 20 years. And, generally, murders involving acquaintences are easiest to solve.
A Department of Justice survey of other violent crimes from 1973 to 1979 showed a high 59 percent also involved strangers. That portion -- closer to 80 percent when it comes to robbery -- has been holding steady in the department's national crime surveys over the last few years.
The question criminologists are asking is, ``Why?''
Economic hardship has always had a close link with crime rates. Statistically, young minority men without jobs in inner city neighborhoods are among the most likely perpetrators of crime. They are also among the most likely victims.
But criminologists find in a growing number of cases that commission of one kind of crime, such as robbery, often escalates into another, such as assault or murder.
``Not all of these homicides appear to be what we'd call economically motivated,'' comments James D. Wright, a sociologist with the University of Massachusetts who recently completed a national study involving a number of interviews with prison inmates. ``Part of the crime problem could be called adrenaline addiction -- just the thrill of confrontation and the inherent danger,'' he notes.
Indeed, in focusing on the reasons for the increase in violence against strangers, experts mention everything from a lack of clear values to mixed signals of what society accepts as conveyed by television and movies.
Gary Stollak, a psychologist with Michigan State University, blames lack of severe punishment for crimes.
``There is a social climate these days which does not necessarily encourage but permits the expression of violence as a way of resolving conflicts,'' he says. ``There is no stigmatization of violence. You don't see any regret expressed by any of the characters [in movies or on TV] who've committed murders. And we've lost the whole concept of prison as a terrible, terrible place to be. . . . For some who are poor and without a job [the prospect of a place] where you can have three square meals a day, wat ch TV, and play basketball is a social world that can make a great deal more sense than being in certain parts of Chicago, Detroit, or Los Angeles.''
Southern Illinois University's Riedel says that face-to-face violence on TV may be less but that violence itself is not down. It has just become more random and impersonal, he says. In his view the hike in actual stranger violence may be linked.
``If you watch the `A-Team' or any of these programs, you frequently see a scene in which a car goes over a cliff and blows up,'' he says.``I don't think we're teaching people who watch this not to commit violence. I think we're teaching them that impersonal violence is OK.''
University of Iowa sociologist Rosemary Gartner, co-author of a new study looking at violence and crime internationally, says she thinks easy access to guns increases the likelihood that a minor crime will turn into a major one. ``Clearly explosive situations where a gun is present are much more likely to be lethal.'' She says she is convinced that stricter gun controls could significantly reduce the number of homicides.
Mr. Stollak, at Michigan State, says he favors field trips to prisons, including chats with inmates, as a regular grade-school project. ``I think every 10-, 11-, and 12-year-old should get a feeling for what it means to commit a crime.''
The rise in stranger violence also suggests a need for added caution in deciding where and when to walk alone. But experts say such concern is easily overdone. They note that elderly women, for instance, worry most about the problem but are statistically among the least likely to be victims. ``You have to be able to read the scene -- but it can get to the point where people start making prisoners of themselves,'' says University of Missouri sociologist Dr. Michael Stein.
Joining a neighborhood watch group can help. While there is little scientific data yet on their effectiveness, experts say the very act of joining a group has positive benefits. ``It forces you to get to know each other and the more you can engender a sense of community, the more likely it is that people will start looking out for one another,'' says Dr. Stein.