"His intent was to kill a child," Nassau County Police Sgt. Vincent Garcia said of 23-year-old Evan Sachs.
Sachs was arrested Friday night, moments after police say he plunged the 4-inch blade of a hunting knife five times into the boy's back.
The child suffered a punctured lung but was expected to survive, said Nassau police Lt. Ray Cote. The stabbing happened at about 8:30 p.m. as the boy was playing in an arcade that is part of a Dave & Buster's restaurant in Westbury.
The boy's parents were only several feet away, but Sachs apparently waited until they were momentarily distracted to begin assaulting him, Cote said. A person who witnessed the attack told the boy's father; they quickly confronted Sachs near a restaurant restroom and held him until police arrived.
Sachs, a Merrick resident, has pleaded not guilty to attempted murder, assault and weapons charges. He is being held without bail pending his next court appearance on Wednesday. Cote said it does not appear Sachs has a criminal record.
Police said the suspect was carrying a typed note indicating his intent to kill a child; the victim was chosen at random. "Anyone of that age and sex would have been suitable," Cote told reporters.
The note also indicated that Sachs had spent several weeks trolling area malls in search of the right victim.
"He's been scouting locations in the area to find an appropriate place to kill a young boy," Cote said.
Defense attorney Eric Sachs, who is not related to the suspect, declined to comment on reports about the note.
"I haven't seen it, so I can't comment on it," he said. "The main focus of my client and his family has been on the little boy. They are more concerned the little boy has a full recovery."
The suspect's mother, Randi Sachs, told 1010 WINS Radio on Monday that she was grateful that the boy was going to survive. She said her son was under psychiatric care at the time of the stabbing.
"We're very sorry for what happened," Randi Sachs said. "My son is very sorry. We hope this young boy is going to be fine."
Of her son, she added: "He needs more mental health treatment."
Sachs graduated in 2004 from Sanford H. Calhoun High School in Merrick and later from the University at Albany, according to Newsday. He was employed as an usher at a Farmingdale movie complex.