PHOENIX â€"  Tucson police are saying for the first time that a 6-year-old girl who vanished from her home last month was abducted.

Investigators had previously characterized Isabel Mercedes Celis' disappearance as a "suspicious disappearance/possible abduction."

Police spokeswoman Maria Hawke says it was an abduction after investigators determined the girl didn't leave her home alone and after they reviewed the evidence. She declined to comment further.

Authorities have been searching for the girl since she was reported missing by her father on April 21. Family members have said they last saw her in her bedroom the night before.

A window was later found open with the screen pushed aside in the family's home.

The Arizona Daily Star had previously reported that police considered the disappearance to be an abduction.