A witness said there was "no pause or anything" before a man was stabbed in the back while trying to break up a fight in Mott Haven, as police search for the suspect more than three weeks after the attack.

Police said the attack happened last month but recently released a photo of the suspect. 

According to police, the suspect got into a fistfight with another person shortly after 10:30 p.m. Oct. 16 outside an apartment complex at 2413 Third Ave., beneath the Third Avenue Bridge.

Then a 38-year-old man intervened, and that is when the suspect allegedly stabbed that Good Samaritan in the back with a knife.  

Police said the victim was taken to Lincoln Hospital in critical but stable condition. 

"As soon as he intervened, the suspect turned around and stabbed him right in the back," said James, a witness who asked to be identified only by his first name. "There was, like, no pause or anything. It was immediate. [The suspect] said, 'Stay out of it,' and then he didn't stay out of it, and then there was a stabbing." 

Anyone with information about this incident is asked to contact the NYPD.