In one case, a 54-year-old man killed one neighbor, wounded another, and then committed suicide. In another case, a 29-year old man was found murdered in his car. A girl who had been with him is missing.
Psychologists say the apparently random wave of unsolved killings could be related to lingering stress from the country's 1992-95 war and the country's chaotic and uncertain postwar period.
"People in Bosnia-Herzegovina are constantly under stress," Aleksandar Milic, a Bosnian psychologist, speaking told RFE/RL's South Slavic and Albanian Languages Service. "They find it hard to cope with large amount of negative facts and events in everyday reality. So what we see as a result is violence, crimes committed for some bizarre reason."
Srdjan Puhaklo, another psychologist, told RFE/RL that such waves of violence tend to feed on themselves as psychologically unstable people react to the news.
"It is interesting that we have this wave of violence," Puhaklo said. "Fragile people react upon getting the news. They take it as a signal that this is an act to be repeated. It spreads like a social disease."
Gojko Vasic, the chief of the crime unit for the Republika Srpska police, where Banja Luka is located, said the wave of killings may just be a fluke.
"It all happened in the past 24 hours, but a month before it was not happening," he said. "And we may not have another [murder] case for the next three months. When we look at the annual average, it is not bad."