NEW YORK (CBSNewYork) — New details emerged Sunday night about the deplorable conditions in a Bronx apartment in which police said four children were living while their parents went to work.

As CBS2’s Ali Bauman reported, the children’s parents were in jail late Sunday.

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Investigators said a 5-year-old boy and his three older siblings – sisters ages 12 and 13 and a 15-year-old brother – were found in a Kingsbridge home with blood stains on the walls and insects crawling on the children.

A deliveryman flagged down police and the parents were taken into custody, police said.

With their heads low, Wilfred Lewis, 59, and his wife, Charlotte, faced a judge for the first time early Sunday morning in what prosecutors called a case of severe child abuse.

According to police, their 5-year-old son was discovered Friday morning alone in the Kingsbridge Avenue apartment. He opened the door when a FedEx worker needed someone to sign for a package, police said.

Investigators said feces and maggots replaced any food at the kitchen, and the boy had not seen his parents since the day before.

“I saw the little boy outside in the hallway with the super and the cops were here, and I quickly heard the conversation about, ‘Oh, when was the last time you saw your parents?’ and he said, Thursday night, I believe,” said neighbor Deanna Strom.

Authorities said the boy’s three older siblings were at school at the time, but had signs of scabies.

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All were taken by protective services, and their parents were charged with four counts of child endangerment.

Both police and the Administration for Children’s Services said the family had no history of abuse, and as soon as the issue came to their attention, an investigation was launched.

“The parents, they looked very humble — every time they used to come in, say, ‘Good morning; good evening,’” said neighbor William Villafane.

Sources said the children’s mother, Charlotte, is a nurse at Montefiore Medical Center – where she was arrested. Sources said the children’s father is a former professor who had recently been working as a Metropolitan Transportation Authority technician.

Neighbors said they never would have suspected the parents were raising their children in complete filth.

“It’s eight hours of work for what you’ve got to work. What is he doing for eight hours in the apartment by himself — no food, animals, roaches, like they say – I mean, it’s very sad,” Villafane said.

Sources said when the father surrendered, he told police that his 5-year-old son is self-sufficient enough to be home alone.

The parents were being held on $15,000 dollars bail late Sunday and were due back in court this week.

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Child services said it was working with police in the investigation.