Authorities finally tracked her down on Manhattan's West Side, thanks to a driver and a traffic agent.
Clutching a bag of gummy bears as tightly as her grandmother was holding onto her, Ava Byrne left the 10th Precinct Friday night, as her mom breathed a huge sigh of relief.
"I am feeling happy and I just wanna go home and spend time with my daughter, thank you," said the mother, Morgan Barella.
An hour later, her dad 24-year-old Robert Byrne walked out the same door, but he left in handcuffs.
"He just hears voices and he listens to what his voices tell him to do, I couldn't tell you," said Ava's grandmother, Debbie Cyr.
Whatever the reason, police say he kidnapped his own daughter from her home in rural Luzerne County, Pennsylvania, and took her on a two-hour journey to New York City.
Ava was wearing only a diaper when she was taken. Her mother says the abduction followed an argument.
"He slapped me across the face, into the closet and tried to grab my phone. He squished my belly, and the last thing he said was he's going to shoot me, my kids and himself. Then he took off with our daughter," said Morgan Barella.
Fearing the girl was in danger, police in Pennsylvania issued an Amber Alert, and a short time later extended it into the New York area.
And barely a minute later, a passerby noticed the Hyundai with Pennsylvania plates at 34th Street and 10th Avenue, and told NYPD traffic agent Md Ali.
"I said sir don't move your car please? Pull over here I talk to you," said Ali.
He flagged down passing police officers Rui Sanchez and Sean Mooney, but by now Byrne was on foot with Ava in his arms, walking east on 34th Street. The police caught up.
"And they caught him right here in front of the building," said eyewitness Kenny Holmes.
The officers took the father into custody with no incident.
"He pointed out the vehicle to us, we did see the vehicle, it was unoccupied at the time and he pointed out the direction of where the individual that was in the vehicle left with the child," said Officer Mooney.
One officer showed the girl videos to keep her calm, as others took her dad into custody.
"They asked him about her birthday and he couldn't remember that," said Holmes.
Domestic cases involving kids are always tough for cops, and no one knows what this family's future will hold. But on this day, the system worked.
"I think it's incredible. We do receive a lot of Amber Alerts and this will be the first time I was ever involved," said Officer Mooney. "This is a great day, it really is."
"Thank you for whoever anybody who helped. Thank you very very much we're very happy," said Debbie Cyr.
Ava is okay, but was taken to the hospital to be checked out.
Robert Byrne is awaiting extradition back to Pennsylvania.