Though the lack of hard evidence doesn't give the families closure they want, Orrey said, it could mean the girls are alive somewhere.
"It's a mixed blessing either way," she said. Both lieutenants said that if it turns out the Garridos were not involved with the girls' abductions, they hope the attention brought to their cases will yield tips that could lead to a resolution.
Orrey said the search could continue into next week, though it will be suspended over the weekend both to cut costs and to give investigators a much needed break.
"Jaycee, her daughters, and I are grateful for everyone's generosity, kindness, and good wishes these past few weeks," Terry Probyn said in a statement provided to ABC News by former U.S. attorney McGregor Scott. "Thank you. All of us are doing very well under the circumstances. We especially appreciate everyone recognizing that what we need most right now is to be allowed to become a family again within a zone of privacy and security. We hope that our story focuses attention on all of the children still missing, and on their need to be found. We must keep looking for them. As Jaycee shows, miracles can happen."
A trust fund for Jaycee Dugard was set up following her rescue, the address for which is below.
Jaycee Dugard Trust Fund
c/o View Tech
P.O. Box 596
Atwood, CA 92811
The Associated Press and ABC News Correspondent Brian Rooney contributed to this story.