Police: Suspect in children's stabbings arrested, had been released on parole

New York (CNN) -- DNA evidence from a knife helped police identify the man who allegedly stabbed to death a 6-year-old boy and critically wounded a 7-year-old girl on a New York elevator, a law enforcement official said Wednesday.

The crucial evidence was retrieved from the Dura Edge knife the man allegedly used in the Sunday evening attacks, the official said. The knife was recovered at the scene.

New York Chief of Detectives Robert Boyce said in a news conference Wednesday that there is a person of interest and the case 'picked up a significant amount of steam.'

Police Commissioner Bill Bratton told reporters, 'We have had good numbers of tips coming in on this stabbing case, and we want to thank the public for reaching out.'

Children stabbed in a New York elevator The suspect has been described as a 'heavy set' male, approximately 6 feet tall, between ages 25 and 35.The suspect has been described as a 'heavy set' male, approximately 6 feet tall, between ages 25 and 35.

The stabbing occurred inside an elevator of the apartment building where the children live in the East New York neighborhood of Brooklyn, police said.

Prince Joshua 'PJ' Avitto was stabbed in the torso and transported to a nearby hospital, where he was pronounced dead. The girl was also stabbed in the torso and was in critical condition, according to police.

Bratton said Monday that the children were on their way to get ice cream when they were stabbed.

Families of both children have been coping with grief and struggling to comprehend the situation.

'It's two children. It doesn't make any sense,' said Scott Avitto, PJ's uncle. 'We're all just struggling, we're trying to pull it together. Our family is strong, but we just want justice to be done.'

'Pray for her, and us. And pray for PJ's family. This is senseless. I don't know what monster would do something like this,' Regenia Trevathan, the girl's great-grandmother, told CNN affiliate WCBS. She said adults were watching the children outside on a playground when they went inside the building alone to get ice cream.

Avitto was related to Taj Gibson, a forward for the Chicago Bulls. Gibson tweeted Monday morning: 'They killed my lil super man. #rippj only two more weeks until your 7 birthday. Tears forever.' Gibson also posted a picture of Avitto to his Instagram account.

PJ's godfather Henry Alston said the boy's funeral will be Friday.

Investigators were considering the possibility that the suspect may also be responsible for another fatal stabbing that occurred just blocks away.

Tanaya Copeland, 18, was found in the same neighborhood Friday night, unconscious and unresponsive with multiple stab wounds to her torso. Copeland was pronounced dead at a nearby hospital, police said.

The close proximity of the incidents, as well as similarities in the type of weapons used, have led detectives to believe the two cases may be related.

'We have to proceed as if they are aligned,' Boyce said of the three stabbings. 'The knives are very similar. The proximity is four blocks. We have a basic description of the male.'

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CNN's Adam Reiss and Shimon Prokupecz contributed to this report.