NEW YORK -- Maybe it was the moon.
What else might have prompted a 20-year-old Boston man, his condition diagnosed earlier as "limited but not mentally ill," to embark on a 13-hour stabbing spree that injured four random victims in Manhattan last week?
"Sometimes, extreme acts of violence seem to come out of nowhere," said Jack Levin, a criminologist and director of the Brudnick Center on Violence at Northeastern University in Boston. He said the attackers are usually quickly caught.
"Their crimes are so disorganized and ineffectual that they never run up a large body count," he said. "In a frenzied state, they go from victim to victim without any cooling-off period. The entire rampage is held together by their lack of mental health, and little more."
Last week's stabbings fit the pattern of other multiple attacks that, because of their apparent randomness and short duration, briefly gripped the public's imagination but were relatively quickly subsumed.
In January 2005, Jesse Nettles, 58, stabbed five strangers, including a man pushing his two children in a stroller in Times Square, during a two-day rampage in Manhattan. Nettles, who was homeless, pleaded guilty to assault charges and was sentenced to 30 years in prison. In 1974, he had killed a man at the Port Authority Bus Terminal.
On an afternoon in May 2004, Jose Rodriguez-DeJesus, 29, used a 13-inch kitchen knife to stab three people in Greeley Square, just south of Herald Square in Manhattan, before being shot by the police. He is now serving a 25-year sentence.
He had served 30 months in a Massachusetts prison for stabbing an uncle and was committed in 2000 for a psychiatric evaluation but was not found to be insane. He was described as distraught and volatile, and a relative said he "was into violence; he liked talking about killing."
While they declined to elaborate on specifics of the latest case, several criminologists said it did not seem atypical.
"It's probably the end result of a series of disappointments or stresses this guy has had over the past several years," said N.G. Berrill, a forensic psychologist who teaches at John Jay College of Criminal Justice of the City University of New York. "He could be mentally ill. He feels angry that a girl just dropped him, or he didn't get a job, or his parents kicked him out of the house. This is more like 'I'm going to take my little knife and show people how angry I am.'"
On June 8, Kenny Alexis was released on bail in Boston after a court hearing on vandalism charges. Last Tuesday afternoon, the police said, he was stopped for fare-beating at a subway station near the Port Authority Bus Terminal in Midtown. He was issued a summons after officers found that he was not wanted on any outstanding warrants.
At 3:41 p.m., the authorities say, Alexis stabbed a 21-year-old tourist from Texas on a subway train in Harlem, saying later that the man was in his way. About 12 hours later, the police said, he stabbed a 30-year-old Brooklyn man on a subway platform at Rockefeller Center after the victim refused to give up his cell phone.
Then Alexis stabbed two students from Montreal, one 22 years old and the other 25, who were standing on a traffic island in Times Square, after he tried to engage the two women in conversation, the police said.
He was arrested after witnesses to the last attack followed the assailant to a McDonald's and called the police.
All four victims were recovering. "In all likelihood," Levin said of the attacker, "he sought revenge for his miseries, not against any particular individual, but against an entire group of people - all New Yorkers, all Americans, all of humankind."
Police Commissioner Raymond W. Kelly did not resort to folklore to explain the string of stabbings that began in the city's subways.
"When you get 4 1/2 million people a day into the system," Kelly said, "every once in a while a really bizarre thing can happen."