Detectives believe they are looking for the abandoned infant's father, who they say frequents the Times Square area.
In the dashcam video, you can hear the uncle and mom of the 18-month-old child inside the car saying, "Help, help we got a baby in here dying."
"He's a hero, like I would do anything for the man," the baby's mom said. "The man is a hero, he saved my daughter."
It began Tuesday morning, when the baby's parents stepped out of their running car to drop off another child at a bus stop.
"It's a different feeling," said the deputy. "Some nights you go home, and you don't really know if you've made a difference, but in situations like this, you feel it."
The boys were born safely on Feb. 25 but had to remain in the hospital due to their medically sensitive status as premature babies.