A May 5, 2014, photo provided by the New York State Department of Corrections shows Daniel St. Hubert.

NEW YORK - A recently released convict suspected of fatally stabbing a 6-year-old boy and injuring a 7-year-old girl in a Brooklyn elevator is also being eyed in the stabbing of a homeless man days later at a Manhattan subway platform, a police official said Thursday.

Daniel St. Hubert, who was arrested Wednesday night shortly after he was publicly identified as a suspect in Sunday's gruesome attack in a public housing building, appears on surveillance video near the subway stop where a man was stabbed on a platform, said Stephen Davis, the police department's top spokesman.

Witnesses to Wednesday morning's seemingly random stabbing also described a man resembling the 27-year-old suspect using an 8-to-10-inch knife with a brown handle similar to one recovered on St. Hubert when he was arrested, Davis said. The 52-year-old homeless man is recovering in a hospital and is likely to survive his injuries.

St. Hubert is also suspected of stabbing to death 18-year-old Tanaya Copeland on Friday four blocks from where Sunday's attack happened, though more forensic testing at that scene needs to be conducted, Davis said. A similar knife was recovered at the scene of Copeland's slaying.

Investigators are now reviewing all stabbings citywide that have occurred since St. Hubert was released from prison on May 23, following a five-year sentence for attempted murder and assault, police said.

Court records show St. Hubert was arrested in May 2009 after punching his mother in the face, strangling her with an electrical cord and stealing her car. He eventually pleaded guilty in July 2012 and served almost three years of his sentence in city jail or in the custody of the department of mental hygiene, according to court records.

St. Hubert was being held in a Williamsburg, Brooklyn precinct Thursday and unavailable for comment. It wasn't immediately clear if he had made any statements or had asked for an attorney. Davis said it appeared St. Hubert was issued a summons for public urination in Brooklyn on Tuesday night, before he was identified as a suspect in Sunday's attack.

Meanwhile, the father of Prince Joshua Avitto, the 6-year-old boy who was fatally stabbed, said Thursday that if he saw the suspect, he'd ask him, "What made you do this to a little baby?"

"I'm at a loss for words," Prince's father, Nicholas Avitto, told Fox 5 News. "The bottom line is he got out and this tragedy took place after he was released from jail."

"What compelled you to do this? It's unfathomable," added Avitto, who had his son's initials freshly shaved into his hair. The boy's friend, 7-year-old Mikayla Capers, was also critically injured in the attack.

St. Hubert was picked up Wednesday night just after 8 p.m. by detectives who had been tracking him and were patrolling the area around his mother's Queens home, police said. He was identified by forensic evidence recovered on the knife at the scene of Sunday's elevator stabbing, police said.

At a Wednesday evening press conference attended by the mayor, officials said investigators believed St. Hubert had no car and may have been riding the subways. Davis said St. Hubert, who has an extensive criminal history, had previously been arrested on disorderly conduct charges for taking up two seats on the subway and other infractions.

St. Hubert hasn't yet been officially charged but murder and assault charges are likely coming, said Davis.

St. Hubert didn't put up any resistance during his arrest and was angrily ranting to himself in a holding cell late Wednesday night, Davis said.

It wasn't immediately clear what he was ranting about or if he has a history of mental illness, Davis said.

Court records show St. Hubert was found unfit for trial three of the four times he was ordered to undergo psychiatric evaluations following his arrest for assaulting his mother. He also was convicted of assaulting a correction officer in jail, the records show.

The attorney who represented St. Hubert in his attempted murder case didn't immediately return a request for comment.