ALBEMARLE COUNTY, Va. (WVIR) - In the air and on foot, the search for University of Virginia student Hannah Graham stretches out into rural southern Albemarle County.

Saturday a crew of 20 trained search and rescue volunteers used canines and helicopters to search a wide area between Route 29 and Route 20.

Crews say it's a complicated process to set up and search over such a wide area. They start by focusing on high priority areas within the search zone, which are decided based on tips police, receive, and factors like ease of access or proximity to a roadway. Their main focus Saturday was along Route 29 south of Charlottesville.

The University of Virginia donated food and water for the crews. Search coordinator Mark Eggeman says there's not always a lot of evidence gathered, but that doesn't mean they aren't making progress.

"Even if we don't find anything, that's still information because it, to a great degree, is a process of elimination. So even if we go through an area, we don't find anything, it's something we can rule out, we can push on to the next area,” said Eggeman.

The last of the ground search volunteers stopped for the night around 7 p.m. to head home and get ready to head back out Sunday. The area of focus for those search teams then will be along Plank Road, which is also in southern Albemarle County.