Bladimy Mathurin, 47 and Chinwai Mode, 27, were shot and killed at around 10.30pm on Sunday, with the suspect fleeing the scene.
The NYPD said that officers were called to a 911 call at the address on Brooklyn Avenue in East Flatbush to find the two victims in the fourth-floor hallway suffering gunshot wounds to the head and torso.
Both victims were pronounced dead at the scene.
Two days on, no arrests have been made.
On Tuesday, the NYPD identified the suspect as Jason Pass, 47, who lived in the apartment directly below the victims.
NYPD Chief of Detectives Joseph Kenny said that six 311 calls had been made from Mr Pass’ apartment complaining about the noise upstairs since March 2022.
The victims’ family members have said that they had been having issues with the downstairs neighbour for years.
The feud allegedly began when the neighbour grew annoyed with the noise made by the four young children living upstairs.
Over the years, Marie Delille, wife and mother of the victims, claimed that they had tried to talk to the neighbour, explaining they do what they can to keep their children from making too much noise, reported CBS.
But last Sunday, the row allegedly escalated.
Ms Delille said she was in her kitchen doing the dishes when she heard banging coming from downstairs as though the neighbour was pounding his ceiling.
She asked her young children if they were making any noise, to which they replied that they weren’t.
Ms Delille said that her husband started to bang back.
The neighbour came upstairs and an argument between the neighbour and the family escalated, before the suspect allegedly pulled out a gun and fired nine rounds at the victims in front of Ms Dellile’s 10-year-old child.
Surveillance footage from the building obtained byThe New York Post shows a man pacing outside an apartment before a woman emerges and exchanges words with him.
The footage then shows the woman being joined by a man, identified by police as Mode.
The video has no audio, so it is unclear what was said.
Later on, the footage appears to show Mathurin leaving the apartment holding a pair of scissors and confronting his neighbour.
Ms Delille is seen trying to drag Mathurian away.
The neighbour is then seen pulling out a gun from his pocket, which Mathurian appears to wave off as he walks back to his apartment.
After this, the suspect allegedly shot both the father and his stepson.
“I went outside, I tell my husband, ‘Leave him alone. Come. Come. Get inside’,” Ms Delille told New York Daily News.
“I could hear a voice telling me, ‘Get inside.’ When I was turning my back, he shot my husband. I didn’t know of my son. I thought my son was inside. My husband went out first. Had an argument with him. That’s when my son went out.’”
Some of the children in the apartment witnessed their father and brother being killed, Ms Delille said.
"I need justice to be served," Ms Delille she said.
The family have requested increased security from police at the apartment block until the suspect is found.
Ms Delille also denies claims that her husband confronted the suspect with a weapon.
“My husband had no gun, no weapon,” she told shooting-ny/13994410/">ABC7. “Why did you bring a gun to shoot my family? Why would you bring a gun to tear my family apart?”
Police told The Independent that the investigation is ongoing and no arrests have yet been made.