The switch in the search's focus came after a Superior resident reported finding a backpack with a water bottle with Jessica Ridgeway -- the name of the missing girl -- written on it, The (Boulder) Daily Camera reported.
Westminster police spokesman Trevor Materasso said investigators had yet to confirm whether the backpack, which was found about 6 miles from where Jessica was last seen, belonged to the girl.
"We've been looking for a lead, and this is possibly that," Materasso told reporters.
Police employed a bloodhound to search the area where the backpack was found, he said.
Police closed roads into the neighborhood to non-residents and officers searched the trunks of residents entering the area, the newspaper said.
More than 800 volunteers worked into the night Saturday searching for the girl, who was last seen by her mother Friday as she walked out of sight headed to a park 3 blocks from her home to meet classmates and go to their Westminster elementary school. Classmates say Jessica never showed up at the park, The Denver Post reported.
Police used canine search teams and organized community volunteers into 50-person search parties combing the area. Police divers equipped with sonar scanned a nearby lake for the girl's body but turned up nothing, Cheri Spottke, a police department spokeswoman said.
Police said more than 100 tips had come in about the girl's potential whereabouts and all were being investigated.
Police went gone door-to-door asking for permission from neighbors to search their homes. Most complied, Spottke said.
The girl's mother, who works an overnight shift, slept through a phone call from the school saying Jessica hadn't arrived and police weren't notified of her disappearance until about 4:30 p.m. Friday, the newspaper reported.
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