PICHER, Oklahoma - The search for two teenage girls missing for 20 years is getting the attention of the federal government. 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.

Representatives with the OSMRE have a special camera and lighting equipment to help examine mine shaft floors and evaluate the integrity of the shaft walls.

On December 30, 1999, investigators found the bodies of Ashley's parents in their burned out mobile home in Welch, but Ashley and her friend, Lauria were nowhere to be found. Investigators said three men kidnapped the 16-year-old girls, killed them, then dumped their bodies somewhere in the Picher area.

Investigators wanted to make it clear they do not have absolute information that the girls are in a mine shaft. Tuesday, the first of a two-day search, was about assessing exactly where to search with the cameras on Wednesday.

The day began with a caravan of investigators making their way up a chat pile to get the lay of the land in Picher. The latest search effort comes just days after the 20th anniversary of the day the two girls went missing.

"The day of the anniversary, we got two tips that we follow up," said Lorene Bible, Lauria's mother. "It doesn't stop. People still contact us."

Investigators plan to look at four mine shafts. They used a fishing pole to measure how deep the shafts are before they put cameras in Wednesday.

Hydrologist Dr. Brian Hicks with the OSMRE explained some of the technology of the borehole camera that will be used.

"I wouldn't say it's the most up-to-date technology. This particular camera system is maybe 10 years old," Hicks said.

The federal agency is the latest to join more than a dozen others, along with volunteers, working to find answers in the case. It's the first time the federal agency has used their equipment to search for human remains. The OSMRE came to Picher after U.S. Senator Jim Inhofe reached out to federal agencies, hoping to bring more resources and expertise to the search efforts.

"Everyone wants to bring these girls home," District 12 District Attorney's Office Investigator Gary Stansill said.

A Tulsa geologist even brought his personal underwater drone to help with the search.

No matter how much technology there is, Lauria's mother said there's still missing information.

"I just feel that there's still somebody that has the key to it, where we can go find the girls," she said. "And they can remain anonymous."

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.