The search for a 6-year-old Arizona girl has intensified after FBI-trained dogs found something said to have interesting investigators.

At around 8 a.m. Saturday, April 21, Isabel Celis was reported missing by her father who discovered she was missing when he went to wake her up after her mother left for work. The 6-year-old was not in the room and investigators say the window was open, with the screen removed.

She was last seen Friday night at around 11 p.m when she was put to bed,

Though police have upgraded the search from a missing child to a possible abduction, Isabel’s parents have not been ruled out as suspects.

More than 250 people took part in the ground search in Isabel’s Tucson neighborhood. Air and K-9 unit searches are ongoing as well.

Police spokeswoman Sgt. Maria Hawke told ABC News, “We don’t have an actual piece of evidence that points us in one direction or another, so, for example we don’t have a piece of evidence that says she was definitively taken from the residence. We don’t have any specific piece of evidence that tells us she left the residence on her own.”