The city's medical examiner needs further testing to determine what killed a 3-month-old baby inside an unlicensed SoHo day care after the initial autopsy was performed Tuesday, authorities said.

It was baby Karl Towndrow's first visit to a day care center at 69 Greene Street, which has been operating for about 14 years without a license, said Chief of Detectives Robert Boyce at an unrelated news conference.

His mother, who worked nearby, dropped him off and was supposed to come back to feed him at around noon. But just before 12:15 p.m., police got the harrowing call: Karl's lips had turned blue.

"At some point the mother was supposed to come back, who worked nearby ... to feed the baby at around noon. Before that happened this occurred," Boyce said. "Originally the child was fed by one of the workers there and afterward she discovered the baby's lips had turned blue and rushed him to the hospital.

"The mother worked nearby and she had recommendations of the location from people who worked in the community," Boyce added.

The child, who's family lives in Brooklyn Heights, was taken to Lenox Hill Hospital where he was pronounced dead.

The nursery was closed Tuesday, Boyce said. During the chaos on Monday, there were about 15 children ranging from about 3 months old to 3 years old as well as four employees, including the owner, at the day care.

A fundraising page for Karl was set up on the site gofundme: Remembering Karl Towndrow. The page had raised more than $3,000 by Tuesday afternoon.

"Karl was beloved by his parents, who doted on him every moment," someone wrote on the fundraising page. "He was their joy and brought happiness to everyone who met him. His family and friends are grieving but are taking comfort in knowing they knew this sweet, innocent soul, even if it was all too brief."

The money would go toward funeral expenses and support for the family, according to the page.