Lev Vayner was discovered inside an apartment on Overlook Terrace at around 3:15 a.m. Monday.
He was stabbed in the neck and abdomen and pronounced dead at the scene.
The suspect, 45-year-old Alon Riabichev, was arrested and charged his murder and criminal possession of a weapon.
Riabichev apparently had called 911, said he had a mental breakdown, and stabbed the victim, authorities said. When police arrived, he was allegedly sitting in the kitchen with the knife on the table.
According to the victim's family, he was trying to help Riabichev out and apparently it ended in tragedy.
Neighbors in the building said they watched the suspect grow up and they knew him. They didn't want him living on the street but Vayner's kindness may have cost him his life, police say.
"He was a very generous guy, he was always out here offering me cigarettes telling me about his time in the Russian army," said resident Moses Waterland.
Neighbors say Vayner was a fixture in his building, but so was the man accused of stabbing him to death.
For several weeks, building residents say he had been living in the lobby after his mother in the building evicted him from their apartment.
"The whole building felt bad for this guy, because I mean we all knew him and when stuff starting going down with his mom, you had to walk by him everyday," Waterland said. "The guy was suffering. He's lived here for a long time. You don't wanna just kick him out onto the street right away, but at the same time you saw he was sliding downhill pretty fast."
Riabichev has five previous arrests with the most recent in 2008.
The medical examiner will determine the official cause of death.
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