Now, the NYPD is plastering the neighborhood with posters, asking for the public's help in the investigation.
The boys were discovered wrapped in brown paper outside the College Avenue building in the Claremont section by the superintendent on November 9.
On Wednesday, the Medical Examiner determined their cause of death to be blunt force trauma to the skull.
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Officials say the newborn boys were found on a back patio and that evidence suggested they had just been born.
Police announced Thursday that the victims appear to be full-term twins, weighing 5 and 6 pounds.
A canvas of the apartment building and neighboring buildings turned up no witnesses, and no one remembers a pregnant woman living in or visiting the building.
Surveillance video revealed no suspicious activity, and a search of the garbage turned up nothing.
Detectives say they have made some progress, they are using DNA from the boys to try and find relatives, but they still need more clues and tips to figure out who killed the infants.
The reward for information that leads to an arrest has been increased to $10,000, and anyone with such information is urged to call the NYPD's Crime Stoppers Hotline at 1-800-577-TIPS (8477) or for Spanish, 1-888-57-PISTA (74782).
Callers can remain anonymous.
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