The Brooklyn dad whose son was brutally killed in an elevator on Sunday evening said Tuesday he instantly recognized the police sketch of a “schizo” man wanted for the senseless slaying.

Nicholas Avitto, 56, said the drawing of a suspect — wanted in the killing of 6-year-old Prince Joshua Avitto — strongly resembles a homeless man he’s seen lurking in their building before.

“I recognize him. That’s the guy who killed my son,” Avitto said. “Police need to check all shelters. He might be in a shelter.”

He added: “I see that sketch and I recognize that individual. I’ve seen him in the hallway. That’s the guy, he’s homeless, he might be in the shelter sitting back, laying back, thinking nothing’s gonna come his way. Police need to check it.”

The 6-year-old boy and his 7-year-old pal Mikayla Capers were knifed on Sunday night as they rode an elevator in their Schenck Avenue building. Mikayla survived the attack but is still listed in critical condition.

“Unstable. The guy’s on medication. I guess he had a mental breakdown or whatever but the guy’s on medication,” said the grief-stricken Avitto, who walked his little boy’s backpack to school on Tuesday.

“As a matter of fact, he’s a schizo. As soon as I saw that picture today on the news, I went to take my son to school like I do every day, and when I saw that picture, it dawned on me this guy is a homeless guy.”

Cops confirmed they’re scouring the city’s homeless shelters and mental hospitals, searching for the lunatic who also might have fatally stabbed 18-year-old Tanaya Grant-Copeland two days earlier, just blocks away from Sunday night’s attack.

“We certainly believe the person who did this might have some mental illness,” said NYPD Chief of Department Philip Banks.

The dad’s ID of the police sketch is a compelling development, according to Banks.

“When he says that he believes that, it’s a real good possibility and that’s an area we’re looking at,” Banks said.

Police are worried that if they don’t collar the killer soon, he’ll strike again.

“Absolutely, that’s a major, major concern,” said Banks, asking for the public’s help.

“We very seldom solve crimes without the help of the community, so we need them to do is, one, be vigilant as much as they possibly can and, two, move around in pairs and keep their eyes and ears open. “

Banks added: “If history repeats itself, it’s going be someone from the community who’s going to see something and give that to us in a timely manner. We’re going to solve this with the help of the community. We need them to be aware.”

Additional reporting by David K. Li