The mother, identified only as a 17-year-old Mount Vernon girl, was located because of media attention given to the case, police said.

"The investigation to this point indicated the young mother was scared and frightened and had concern for her baby, which caused her to place the child in a location where he would be found," Sgt. Mark Shipman said in a statement.

The mother was offered medical care and police said she would be released to a family member.

The healthy infant, swaddled in a blanket, was apparently less than a day old when he was left outside the church Sunday, sometime after the 9:30 a.m. Mass began. He was found by worshippers shortly before 11 a.m. Sunday and taken to a hospital.

The baby is under the protective custody of police. State Child Protective Services will be responsible for placement of the boy once he is released from the hospital.

Once police have finished their investigation, they will forward it to Skagit County prosecutors for review, Shipman said.

Moms Can Give Up Newborns Safely, Legally

Under state law a baby up to 3 days old may be abandoned without penalty if given to an employee or volunteer at a fire station or hospital. The amnesty does not apply when babies are left at churches or other houses of worship.