NEW YORK -- A Boston man accused of a stabbing rampage in and out of the New York City subway system admitted that he attacked four victims and explained why he had done so, a prosecutor told the court Thursday at the defendant's arraignment.

Images: Multiple Stabbings In Manhattan

Assistant District Attorney Christopher Ryan also disputed reports that Kenny Alexis, the defendant, is homeless or "deranged" as news reports have said. Ryan said Alexis lives in Boston with his family who know nothing of his "mental health issues."

Ryan said the defendant's family reported that he comes to New York frequently, stays a few days and returns to Boston. "He came to New York to commit crimes," the prosecutor said. He added that Alexis has a record as a petty criminal in Boston.

Police Commissioner Ray Kelly had previously said the 20-year-old was homeless.

Alexis was arraigned in Manhattan Criminal Court on four counts of attempted murder, four counts of assault, and two counts each of robbery and attempted robbery. The defendant entered no plea during the proceeding.

Alexis' Legal Aid Society lawyer, Candace Kurtz, asked the judge to order a psychiatric examination for the defendant. "I believe he is mentally ill," Kurtz said. "It is my opinion that he cannot assist in his own defense."

Judge Patricia Nunez ordered Alexis kept in jail without bail and directed that he have a psychiatric exam to determine whether he is fit to stand trial. Nunez scheduled the defendant's next court appearance for July 13.

Ryan said the "distinctive" knife Alexis used was recovered. "It is the knife that he used throughout his crimes throughout the evening," the prosecutor said.

Police also lifted Alexis' fingerprints from the subway seat where the defendant sat across from his first victim, the prosecutor told the court, and numerous victims and witnesses identified the defendant in lineups.

"The defendant confessed to each of the incidents and gave reasons for doing what he did," Ryan told the judge. He added that the reasons may not seem rational to most people but he had his motives.

Alexis is accused of knifing four people during a stabbing spree that began shortly after 3 p.m. Tuesday when he allegedly stabbed Christopher McCarthy, 21, of Houston, in the chest with a knife on a train at West 110th Street in Manhattan.

Ryan said McCarthy's aorta was punctured, nearly killing him, and he now faces a lengthy hospitalization and recovery.

Alexis stabbed him "because he was in his way," Ryan told the court.

The defendant's next victim was Ambrosio Castro, 30, of Brooklyn, one of two Mexican men who were waiting on a subway platform in Rockefeller Center when he was stabbed twice in the stomach and chest.

Ryan said Alexis demanded Castro's cell phone. Castro, not understanding what Alexis was saying, failed to hand it over and Alexis stabbed him, the prosecutor said.

Alexis later tried to shoplift from a deli at 58th Street and Broadway in the theater district, Ryan said. He said two employees confronted him but when the defendant threatened them with a knife they let him leave.

Around 4:15 a.m. Wednesday, two Canadian women, Melanie Carrier, 22, and Audrey Perrier, 25, were crossing Broadway at 47th Street when Alexis allegedly approached the women and stabbed each in the back before fleeing.

Ryan said Alexis tried to chat the women up and when they politely declined to speak with him, "he stabbed them and called them derogatory names."

Ryan said one of the women was stabbed in her spinal column, and while the spinal cord wasn't cut, which might have left her paralyzed, the wound did cause leakage of spinal fluid that left part of her nervous system vulnerable to infection.

Two good Samaritans, who were each unaware that the other was following Alexis, trailed him to a McDonald's where police eventually arrested him, Ryan said.

Ryan said Alexis faced as much as 60 years in prison if convicted of all charges.