On Saturday night, Chen had apparently been acting in such a way that concerned Li, Banks said. She tried to call her husband, who wasn't home, but couldn't reach him.
Banks said Li called her mother-in-law in China, who also was unsuccessful in reaching her son. The mother-in-law reached out to her daughter, who lives in the neighbourhood, Banks said.
She and her husband came to the house and banged on the door, then called police. Officers in the area investigating another matter responded, Banks said.
"It's a scene you'll never forget," he said. The victims had wounds in their necks and torsos.
Chen was in custody and wasn't immediately available to comment. He also faces counts of assault on a police officer, which happened while he was being processed, and resisting arrest, Banks said.
Bob Madden, who lives nearby, was out walking his dog when he saw a man being escorted from the building by police. He was barefoot, wearing jeans, and "he was staring, he was expressionless," Madden said.
Yuan Gao, a cousin of the mother, said the man had recently moved to the area and had been staying with different people.
Fire department spokesman Jim Long said emergency workers responded just before 11 p.m. to an emergency call from a person stabbed at the residence in Sunset Park, a working-class neighborhood of adjoining two-story brick buildings with a large Chinese community.
Neighbour May Chan told the Daily News it was "heartbreaking" to learn of the deaths.
"I always see (the kids) running around here," Chan said. "They run around by my garage playing. They run up and down screaming."
-AP