PORTLAND, Ore., June 14 (UPI) -- The massive effort to find a missing 7-year-old Oregon boy has ended after 10 days, and officials say the case is now a criminal investigation.
Searchers and rescue teams gave up looking Sunday after finding no sign of second-grader Kyron Horman, missing since June 4, The (Portland) Oregonian reported.
Some have vowed to keep looking.
"We will be continuing this investigation," Multnomah County Sheriff Dan Staton said. "It is not going to stop, and I am not going to cease in dedicating resources to locating Kyron."
The child, last seen at his elementary school walking to class in the morning, wasn't reported missing until later that afternoon when his stepmother called the school saying he wasn't on the school bus.
The search was one of the largest in Oregon history, with more than a thousand searchers from Oregon, Washington and Northern California taking part, the newspaper said.
Police say the change from search to criminal investigation is a "natural progression."
Authorities are offering a $25,000 reward for information that leads to the boy being found, the Oregonian reported.
