The child was pronounced dead days after the incident, police said.
Police responded to the family's apartment on Veronica Place in Flatbush after the infant's grandmother called 911 for a wellness check just after 7:30 p.m. on Saturday.
Southern California officials discussed the presumed death of baby Emmanuel Haro, saying they believe his parents abused him over time.
Without treatment, babies who are asymptomatic at birth can begin to show signs of the disease weeks, months or years later.
The baby's parents, Ruben Santiago, 36, and Caitlin Gibson, 28, are charged with murder.
Someone spotted the fetus in front of an apartment building on Union Street in Crown Heights on Thursday evening.