An 80-year-old Manhattan man who was stabbed to death had let his accused killer stay in his home because the man had nowhere else to go, prosecutors said.

A grand jury indicted Alon Riabichev, 45, on one count of second-degree murder in the death of Lev Vayner, officials said. First responders found Vayner dead in his Washington Heights apartment on Overlook Terrace near West 184th Street on Nov. 24, according to the Manhattan district attorney’s office.

Riabichev had been living in the hallways of the building after his mother, who also lived there, kicked him out, prosecutors said. Vayner, who had health problems and lived with his daughter, invited Riabichev to sleep in his apartment and use it to shower, officials said.

"Mr. Riabichev allegedly took advantage of his hospitality in the most brutal way and repeatedly, fatally stabbed him," Manhattan DA Alvin Bragg said in a statement. "This ruthless murder is beyond devastating, and my thoughts are with Mr. Vayner’s loved ones as they continue to mourn his painful loss.”

Just before the attack, Riabichev went to a nearby store and bought an 8-inch knife, then returned to Vayner’s apartment, according to the indictment.

Police say Riabichev called 911 around 3:15 a.m. the next morning, telling the operator he’d had a “psychotic break” and “killed somebody a few hours ago.”

Responding officers found Riabichev sitting on Vayner’s bed in the living room, according to prosecutors. Vayner was on the floor near the dining table with multiple stab wounds to his torso and neck. The knife was found on the table, covered in what appeared to be blood.

An attorney for Riabichev could not immediately be reached for comment.