Search teams in Oregon have not been able to find a seven-year-old boy who simply vanished from inside his Portland elementary school 10 days ago.

Law enforcement authorities have announced Kyron Horman's disappearance is now being treated as a criminal case.

"With the search and rescue mission completed at this time, we are moving operations toward a criminal investigative end of the spectrum," said Capt. Monte Reiser of the Multnomah County Sheriff's Office.

After days of hard searching through relentless rain and thick brush or forest, the search and rescue teams from all over The Beaver State have returned to home.

However, authorities say this doesn't mean they're giving up the hunt for Horman.

"It's not going to stop and I am not going to cease in dedicating resources into locating Kyron," said Multnomah County Sheriff Dan Staton.

Investigators have refused to say much about why they have switched to a criminal investigation, but they have announced a $25,000 reward for any information about the missing boy.

It's a tough transition time for family and friends of Horman.

"You mean everything to us and until you come home this family's not complete," said Tony Young, the boy's stepfather. "Please Kyron keep up the hope."

"Our focus has been and will continue to be finding Kyron. So it doesn't change what we"re doing -- getting his face out to as many people as possible," explained family friend Becky Owens.

Volunteers will continue to pass out t-shirts with Horman's picture on them, keeping his image in front of the public.