Investigators in the Zahra Baker case are using GPS devices to pinpoint an exact location in an area landfill where a key piece of evidence might be located.
Crews continued a search Thursday of the Foothills Environmental Landfill in Caldwell County for the piece of evidence, which police will not identify.
Hickory Police Chief Tom Adkins said Wednesday during a press conference that the piece of evidence, if found, will provide a "good, solid timeline" in Zahra's case.
Crews, however, aren't searching for Zahra's body in the landfill, Adkins said.
The landfill, located on Cheraw Road in Lenoir, spans 645 acres, with about 40 acres currently used for landfill operations.
Searchers used GPS devices on landfill equipment to download coordinates of where the piece of evidence might be based on the date and time it was deposited at the landfill, said B.J. Fore, a spokesman for the Caldwell County Sheriff's Office.
Fore said police have a specific timeframe in mind of when the piece of evidence arrived at the landfill, but they are not releasing what that date is.
Maj. Clyde Deal with the Hickory Police Department said investigators already established a specific location to search in the landfill before the investigation started.
The search could take five days, because "anything (searchers) pull up, they're having to move," Fore said.
About 20 people are searching the site, including representatives from Hickory Police Department, the State Bureau of Investigation and the Federal Bureau of Investigation.
Using GPS devices in the investigation helps locate specific places to search, but it also helps eliminate locations, Fore said.
The landfill opened in 1998 and is owned by Caldwell County. The site receives 1,200 tons, which is about 2.4 million pounds of trash daily, according to the Lenoir News-Topic. Foothills Environmental is a subsidiary of Republic Services of North Carolina, LLC.
Searchers spent time Thursday looking at a mattress found in the landfill, but Fore couldn't comment on whether a mattress is the piece of evidence police need.
Crews searched the landfill Wednesday, and Fore said investigators continued the search with fewer men than originally expected.
"They scaled back the number of men, but not the intensity," Fore said.
He said having fewer people in the search area near pieces of heavy machinery ensures the safety of everyone involved in the search.
Crews will search the site daily when the landfill is open. When the site closes, the area will be secured by sheriff's deputies to ensure the investigation isn't compromised.
Zahra's father, Adam Baker, reported her missing Oct. 9, and the search for the 10-year-old turned into a homicide investigation several days later.
As crews searched the landfill Wednesday for information regarding her disappearance, a Catawba County judge raised the bond for Zahra's stepmother, Elisa Baker, saying she was a flight risk.
Elisa Baker is charged with felony obstruction of justice after she allegedly wrote a phony ransom note found at the Baker house in Hickory the day Zahra was reported missing.
Hickory Police Department remains in contact with Zahra's biological mother, who lives in Australia.
"She has provided us with any information she can provide," Deal said, adding there is a possibility Zahra's mother will travel from Australia to the U.S.
Adkins said Wednesday that tips in the investigation led police to search the Caldwell County landfill.
The Lenoir News-Topic contributed to this report.