Man accused of stabbing ACS Cantonese interpreter in his home

A man is in police custody after being accused of stabbing a woman inside his Sunset Park home Thursday night.
News 12 is told the woman is a Cantonese interpreter who is contracted by the New York City Administration for Children's Services and was at the suspect's home checking in on an open ACS case for child neglect. 
It happened around 8 p.m. inside 536 52nd St. 
Investigators say when they arrived on scene they found a 56-year-old interpreter with a stab wound to her back.
Police say the contracted interpreter, along with a female ACS worker, were at the home checking in on open ACS case against her suspected attacker, 61-year-old Guanyi Seng's,grandchildren. 
At some point while they were talking to Seng, police say he started to get upset. When they tried to leave they say he grabbed a kitchen knife and stabbed her in the back.
He is now charged with felony assault and tampering with physical evidence, because police say he tried to dispose of a knife. He was unsuccessful, and that knife has been recovered.
The woman was rushed to the hospital but is expected to survive.