Police on Monday were searching for a woman who allegedly posed as a nurse to kidnap a newborn while the infant's mother was tending to one of her other children near her Texas home.

An Amber Alert was issued for Priscilla Nicole Maldonado, who has jaundice and needs medical care. The alleged abductor finagled the mother into disclosing her home address under the pretense of checking on the infant's health, police said. The infant has been missing since Sunday, when she was only four days old.

“She appeared at the hospital in scrubs,” Lt. Roy Bassett of the Lubbock Police Department said. “The nurses assumed she was [a friend] of the family’s.”

The woman, who told the baby's family her name is Lisa Stewart, “made her way into the mother’s confidence” with repeated visits to the hospital room and home and by calling Priscilla "beautiful" and saying the 5 1/2-pound infant should be entered in pageants, Bassett said.

"I said, 'No, my baby is sick. She can't be out in public,'" the infant's mother, Erica Ysasaga, told KAMC-TV of the woman's baby pageant comment. "She said they would pay me $100 and my baby would win stuff."

Priscilla was being treated for jaundice, a common medical condition in which too much bilirubin -- a compound made during the breakdown of hemoglobin from red blood cells -- is circulating in the blood, according to WebMd. The condition causes a yellow pigmentation in the skin, eyes and mucous membranes, and usually goes away with treatment.

The woman being sought visited the family under the pretense that she was checking on the baby’s health and said she would give the infant a swing and some clothes, police said.

"She was concerned all the time about my baby so I thought she was a nurse," Ysasaga said.

The woman stopped by the family's home on Sunday afternoon and requested to show Priscilla to a relative who she said lives in the neighborhood, the Lubbock Avalanche-Journal reported Monday.

She gave Ysasaga a false driver's license and Social Security number in attempts to reassure her, police said.

Ysasaga and the woman, who held the baby, then walked toward a house the woman claimed belongs to her relatives. Ysasaga suggested they turn back, but as they did, she was distracted by her toddler son and when she looked up, the woman and Priscilla were gone, the Avalanche-Journal reported.

"My son ran ahead of me so I tried to reach over and grab him and when I did that, I turned around, just like that, my baby was gone," Ysasaga said.

Authorities do not believe the woman is an employee of University Medical Center, the hospital where the infant was born, based on the color of the medical scrubs she wore and that she was not wearing a name tag.

"At the very least, she has local ties," Bassett said.

No one at the hospital was familiar with her and there was "nothing to indicate right now that she was an employee of any kind," Bassett said.

"To the best of our knowledge, it's not an employee of our hospital," said hospital spokesman Greg Bruce. "The description of what the employee was wearing, how the employee was acting while they visited with the mother in the hospital is not consistent with any of our staff."

While the mother was in the hospital, the suspect had asked questions about the baby and sometimes helped Ysasaga with small tasks such as retrieving towels, the family said.

"She knew a lot of things that sounded like a nurse would know," Priscilla Madrid, the missing newborn's aunt, told the Lubbock Avalanche-Journal.

Police were interviewing UMC employees who worked the floor during the time Ysasaga and her infant were in the hospital.

In addition, "we've got some objects that we're looking at to see if there's any forensics value," Bassett said. "This was something that was planned over a period of days."

Police were working with the family to make a sketch of the woman and checking surveillance video from the hospital.

Police said the woman police are searching for is Caucasian, between 140 and 150 pounds and 5 feet, 4 inches tall. The dirty blonde last was seen in a red dress with yellow flowers and was said to be in her 30s. Police said she might be driving a white van or a red four-door Pontiac Firebird or Grand Am.

Tipsters were asked to call Crime Line at 806-741-1000 or the Lubbock Police Department at 806-775-2817.

FOXNews.com's Heather Scroope and the Associated Press contributed to this report.