PICHER, Oklahoma - Workers with the Department of the Interior were back in Picher Wednesday, using special equipment to help search for two girls missing from Welch for 20 years.

The U.S. Department of the Interior’s Office of Surface Mining Reclamation and Enforcement (OSMRE) is helping investigators look for the remains of Lauria Bible and Ashley Freeman with special equipment. The girls disappeared after a sleepover in Welch in 1999.

Investigators are focused on four mine shafts in Picher. Investigators said it could be a while before they know anything about what’s inside the shafts.

Day two of the search with federal workers brought everyone back to a mine shaft that was looked at in November 2019.

The area surrounding the shaft is full of tree branches and leaves. It is estimated the shaft goes 170 feet underground.

“After all these years, you can only imagine the amount of debris that's buried down in there,” District 12 DA Investigator Gary Stansill said.

Wednesday’s goal was to learn what the OSMRE can see with its borehole camera.

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Stansill said federal workers are also assessing the shaft, trying to figure out how stable it is for any future, more detailed searches.

“It's a slow process, very slow,” he said.

"We're just grateful that people are willing to bring their knowledge and their understanding and look down a shaft that's like this,” Lindey Leforce said.

Leforce is Lauria Bible's uncle. With three other shafts high on investigators' list to look at, he and other family members will continue waiting for answers.

"All kinds of things wander through your mind so you kinda, good thing is you can go for long walks and clear your mind a little bit and hoping that you hear something, 'Hey we found something,' and then you can come back and there's a resolution,” Leforce said.

Investigators stress they do not have specific information that the girls are in a shaft, that’s just what they’ve heard the most during the investigation.

Ronnie Busick is the only suspect in the case still living.

Investigators are asking anyone with information to call the OSBI tip line at 800-522-8017.