NEW YORK — It was a mistake any tourist could make: Christopher McCarthy, a college student from Houston, boarded an express train instead of a local and wound up in Harlem instead of Central Park.
Moments later, he had turned around and was headed south on a C train when a stranger, without a word, lunged across the car and stabbed him in the chest.
That was Tuesday afternoon. About 12 hours later, it happened again: Two young women visiting from Montreal walked away from their hotel and into the light of Times Square. Both women, ages 22 and 25, were suddenly stabbed in the back.
A homeless man named Kenny Alexis, 21, was arrested minutes after the Times Square attack and confessed to both assaults.
He is also suspected in the stabbing of a 30-year-old Latino on a subway platform. Police also suspect him of pulling a knife on a clerk in a Columbus Avenue deli, who had tried to stop him from stealing beer.
Police Commissioner Raymond W. Kelly said the attacks appeared to be random.
"Based on the facts as we know them so far, there was no contact -- there was no eye contact," he said. "We're going to go forward here and get as many facts as we can, but there is a possibility of being deranged."
The series of attacks came days after New York City celebrated a 1.9% drop in its rate of violent crime -- a drop all the more notable because the nation as a whole saw a 2.5% increase. Cristyne L. Nicholas, head of the city's tourism and marketing organization, said she does not expect the stabbings to interfere with another record-breaking year for tourism.
"A crime like this 15 years ago would have made the police blotter, not the front page," said Nicholas, president and CEO of NYC & Co. "I think it tells you how seriously crime is being taken by New York City's police department and by its residents."
McCarthy, 21, suffered serious chest wounds and was being treated at St. Luke's Hospital in critical but stable condition. His father, Joe, who traveled to New York from Texas, said McCarthy "has forgiven his attacker and hopes he can get help."
The Canadian women -- identified as Melanie Carrier, 22, and Audrey Perrier, 25 -- had returned to their hotel after a night out with two friends, then made their way toward Times Square for an early-morning snack, said Samuel Dupiton, a cabdriver who was parked near Times Square on Wednesday morning.
Alexis approached the women and tried to grope them, then made two quick movements, apparently stabbing each in the back, Dupiton said. Alexis fled into Times Square, pursued by Dupiton and two doormen from the nearby W Hotel. He was arrested moments later, and police retrieved a folding knife with a 3-inch blade. Police said charges were pending against Alexis, whose last known address was a homeless shelter.
Police believe that Alexis is responsible for a third stabbing, which took place at 3 a.m. Wednesday on a subway platform near Rockefeller Center. A 30-year-old man, Ambrosio Castro, was stabbed in the stomach. He and the Canadian victims were treated at St. Vincent's Hospital and were expected to survive.
The stabbings were reminiscent of one of the city's most notorious subway crimes. Brian Watkins, 22, a tourist from Utah, was fatally stabbed in 1990 when he tried to protect his parents from a group of muggers in a subway station. Watkins' murder epitomized the "Clockwork Orange feeling of disorder" in the subway system, said Gene Russianoff, an attorney with the NYPIRG Straphangers' Campaign.
The subways are a far different place now, he said. In the early 1990s, 19,000 felonies took place every year in the subway; now, that number has dropped to 4,000.
This week's stabbings don't suggest any change in that trend, but are "part of the random craziness of life in the city," Russianoff said.