Catherine Goodman didn't notice anything unusual when she first saw the 7-month-old girl and her mother at a New York subway station.
"I held the door for them to get on the subway car, as I always do when I see a stroller," Goodman said.
Several stops later, she got off the train and started walking to the exit -- only to discover the same baby sitting on the platform all alone.
"I saw the stroller and I looked up, and I saw the mom in the subway door just looking at us," Goodman told HLN's Dr. Drew Pinsky.
"And the train pulled off."
Police say the mother, Frankea Dabbs, left her daughter at the Columbus Circle subway station Monday because she felt "she couldn't provide adequate care for the child," New York police Detective Annette Markowski said.
A witness told police she saw a woman push a stroller from the subway onto the platform when the doors opened. The woman didn't get off the train, the witness said.
Goodman said she waited with the baby for the mother to return, but she didn't. Eventually, she called police.
The girl was in stable condition at nearby St. Luke's Hospital. She was not malnourished, though she suffers from a bit of eczema, police said.
Bizarre court appearance
Dabbs, 20, was arrested on charges of abandoning a child and acting in a manner injurious to a child under 17, New York police said.
During her arraignment Tuesday, Dabbs turned toward a camera and said, "Is that thing on? Somebody tell Shawn Corey Carter I said, "(expletive) him.'"
Shawn Corey Carter is the full name of the rapper known as Jay-Z.
Dabbs' father, Frankie Dabbs, said he has no idea what his daughter was thinking.
"She's just a good mother. She was just the sweetest mother ... she took care of the baby, she fed the baby," Frankie Dabbs told CNN affiliate WRAL from his home in Roanoke Rapids, North Carolina.
But the young mother became despondent after her boyfriend -- the baby's father -- was killed, Frankie Dabbs said. He said she witnessed the murder.
"I think it maybe escalated from there," he said. "She was holding all that in."
Aunt: Dabbs was looking for help
The mother told investigators that she was from North Carolina and was homeless, Markowski said. The detective said she didn't know how long Dabbs had been in New York.
Lawanna Edmonds, who said she is Dabbs' aunt, told CNN that the mother had lived with her in North Carolina but left late last week.
Edmonds said Dabbs has had troubles in her life and had been arrested on suspicion of prostitution. Police records also show Dabbs had been arrested in connection with possession of marijuana in 2012.
Edmonds says she understands why Dabbs may have left her child in the subway.
"Everywhere she went for help, people turned their backs on her," the aunt said. "What other alternatives did she have?"