Police said yesterday they have found the mother of the newborn baby abandoned last week in the basement of an Arlington church, a 17-year-old Fairfax County resident who gave birth just hours before the child was discovered.

Cpl. Justin McNaull, Arlington police spokesman, declined to identify the teenager and said that police have not decided whether to file charges against her.

"At this point we're trying to learn everything we can about her and her situation," McNaull said. "When we complete our investigation we'll talk to the commonwealth's attorney's office and decide what should be done."

The baby girl was discovered June 11 in the basement restroom at St. Agnes Catholic Church in Arlington during a prayer service and was baptized Mary Agnes by a parish priest before being taken to Arlington Hospital. The infant was discharged from the hospital Tuesday and sent home with foster parents.

Police said detectives located the child's mother after receiving an anonymous phone call Tuesday. They said the caller had learned of the abandoned baby through news reports and provided investigators with enough information to find the mother.

Police said they contacted the mother's family Wednesday and were searching for her yesterday when her lawyer called to set up an interview with her at the police station.

McNaull would not provide further details, citing the continuing investigation. He would not say where the teenager gave birth -- police had previously said it was not in the church restroom -- and said police do not know why she chose to leave her baby at the church.

He also would not comment on whether the mother's family wants custody of the child. Police and church officials have received calls from many people wanting to adopt the infant.

The Rev. Thomas VanderWoude, the priest who baptized the child, said yesterday that parishioners have been "praying like crazy" for the child and were delighted to hear that police said they had located the baby's mother.

"People are honking their horns as they drive by" the church, VanderWoude said. "They're happy that there's closure to this."

VanderWoude said the church was planning to hold a special mass of thanksgiving last night to recognize the community outpouring and celebrate the child's good health.