A search for a hiker missing in the rugged Craters of the Moon National Monument and Preserve in Idaho led underground, as cave specialists headed into lava tubes looking for the missing physician.

Jodean Elliot-Blakeslee, 69, of Boise, Idaho, and Amelia "Amy" Linkert headed into the Tree Molds area of the monument on September 19 for what park officials believe was to be a day hike. The two were reported missing when they didn't return, and on September 25 Ms. Linkert's body was found in the middle of the lava fields, said Craters of the Moon Superintendent Dan Buckley.

Searchers -- park staff, county sheriff's personnel, and volunteers -- "have cumulatively contributed over 4,000 hours of search time and exceeded 10,000 miles of hiking across treacherous lava flows and scrubby high-desert terrain," a release from the monument said.

On Saturday, the 12th day of the search, the effort also involved cave specialists who were to search lava tubes and caves in the area where the women were thought to have headed.

According to Superintendent Buckley, while there are 340 known lava tubes and caves, "(W)e’re guessing there are probably 3,000-4,000 lava tubes and caves."

Among the roughly 80 personnel searching for Dr. Blakeslee were:

* Eight dog teams

* Idaho Mountain Search and Rescue

* Mountain Home Air Force Base

* Malheur County Search and Rescue

* Blaine County Search and Rescue

* Nine cave specialists from the Silver Sage Grotto cavers group

As Craters of the Moon National Monument and all other national park units are currently closed to the public due to the government shutdown, it has been asked that only approved volunteers contribute to the on-the-ground search. To learn more about the search effort, and to learn how to assist with it, you can visit this Facebook page set up specifically for the search.