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Police arrest suspect in NY stabbings
01:05 - Source: WABC

Story highlights

NEW: Authorities apprehend suspect in stabbing, 27-year-old Daniel St. Hubert

NEW: Police say St. Hubert was out on parole tied to domestic assault since May 23

NEW: Mayor says injured 7-year-old girl "is doing much better"

Prince Joshua "PJ" Avitto, 6, was killed in the stabbing

New York CNN  — 

A New York man released on parole last month pleaded not guilty Wednesday in connection with the stabbing of two children in Brooklyn, one of whom died, authorities said.

Police believe Daniel St. Hubert, 27, was out on parole when he stabbed two young children inside an elevator – killing one of them.

St. Hubert was arrested by detectives around 8 p.m. Wednesday.

He was arrested around the same time that Chief of Detectives Robert Boyce identified St. Hubert by name for the first time as the suspect in the attack.

Detectives were obtaining evidence Thursday that could link him to a fatal stabbing on the subway in the Chelsea neighborhood of Manhattan, the official said.

Investigators were executing search warrants to see if he is linked to additional stabbings since his release from prison last month, another law enforcement official said Wednesday.

St. Hubert has at least nine prior arrests, though police did not specify all the outcomes.

The most recent outcome was May 23, when, Boyce said, St. Hubert was released on parole in connection with a domestic assault case.

Nine days later, police believe he encountered PJ and Mikayla inside an elevator at a public housing complex in Brooklyn. Mayor Bill de Blasio said last week that the two children were “on their way to get ice cream” at the time.

For reasons authorities haven’t yet explained, both children were stabbed in the torso. PJ was transported to a nearby hospital, where he was pronounced dead. “These parents are in such pain now,” de Blasio said.

“These parents are in such pain now,” de Blasio said. “… I ask all New Yorkers to help in this investigation any way you can. Do it for this grieving family. Do it for all of us.”

Police initially said Mikayla was in critical condition. But the mayor last week said: “She’s doing much better. She’s a strong young lady.” A spokesman for New York-Presbyterian Hospitals has refused to comment on her condition. Mikayla was treated for abdominal bleeding and a lacerated spleen, prosecutors said.

A knife believed to have been used in the attacks was recovered at the scene. The bloody knife later tested positive for the defendant’s DNA, authorities said.

As the investigation continues, families of the two stabbed children struggled with the senselessness of the attack.

“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,” said Regenia Trevathan, the girl’s great-grandmother, to CNN affiliate WCBS.

Scott Avitto, PJ’s uncle, similarly said the violence “doesn’t make any sense.”

“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.”

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 are 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. No arrests have yet been made in either case, and the investigation is ongoing, police said.

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

12-year-old girls accused of stabbing friend

CNN’s Kevin Conlon, Ray Sanchez, Adam Reiss and Shimon Prokupecz contributed to this report.