Two weeks after Brigham Young University (search) student Brooke Wilberger (search) disappeared from a parking lot here, police have called off the organized search effort.

Hundreds of volunteers had fruitlessly combed through more than 4,000 acres around this Willamette Valley town, fanning out along railroad tracks, scouring a Christmas tree farm and driving rural roads in five nearby counties, all without turning up any solid clues.

Despite ending the organized search, Corvallis police and the FBI will continue their investigation into the disappearance of the 19-year-old Veneta woman. Wilberger disappeared May 24 from an apartment complex owned by her family near the Oregon State University (search) campus; among the only clues were a pair of flip-flops left in the parking lot.

"We're restructuring the way we're searching," said Lt. Ron Noble of the Corvallis Police Department. "This was decided on consultation with the family."

Authorities have more than 1,700 tips in the case and will maintain the investigation at its current level until all tips are exhausted. There are six "persons of interest" in the case, Noble said. "Then we'll all get together and decide where to go from there."

The FBI will remain on the case. Also participating directly or indirectly in the search are Oregon State Police, the Linn County sheriff's office, and the Philomath and Albany police departments, he said.

With the broad search over, the Benton County sheriff's office search and rescue team will remain ready for a quick response to a specific area or to follow a specific lead, Noble said. The Church of Jesus Christ of Latter-day Saints' stake, where the volunteer search operation has been set up, also has volunteers ready to be called out.