Authorities in North Carolina say they are searching "every piece" of a tree service company for traces of Zahra Clare Baker, a 10-year-old girl who police say is presumed dead and whose father is uncooperative in the case.

Burke County Sheriff John McDevitt said investigators are conducting a "grid search" on Thursday of Real Tree Services in Morganton, N.C., where the girl's father, Adam Baker, works as a laborer.

"We're going to move every piece of everything to eliminate that property today," McDevitt said in an interview with FoxNews.com.

Investigators used hoses late Wednesday to drain a 50-by-70-foot pond on the property for any remains of Zahra, described by family members as an upbeat girl who used hearing aids and a prosthetic leg because of bone cancer. 

McDevitt said the search has so far yielded no clues in the case, saying, "At this point we're just trying to eliminate spots."

A police source close to the investigation also tells FoxNews.com that Adam Baker is not being cooperative in the search for his daughter. 

"His cooperation wasn't good," the source said. "And his credibility is certainly a question now." 

Zahra, of Hickory, N.C., was reported missing on Saturday by her father and stepmother, Elisa Baker, who remains jailed for allegedly trying to throw off investigators with a fake ransom note.

Police say Elisa Baker, 42, confessed to leaving a fake $1 million ransom note on the family's car. The handwritten note, which was addressed to Adam Baker's boss, said: "Mr. Coffey, you like being in control who is in control now we have your daughter and your pot smoking red head son is next unless you do what is asked 1,000,000 unmarked will be in touch soon [sic]."

Baker showed little emotion as she faced a judge Wednesday over a felony obstruction of justice charge that could bring her up to 30 months in prison if convicted. Her court-appointed attorney, Scott Reilly, said she was "scared to death" and very emotional about everything.

Authorities shifted their focus to Adam Baker's workplace -- 19 miles away from the child's home -- after K-9 units detected a "hit" at the site. McDevitt said the tree service company has a lot of equipment -- including a wood chipper -- that police want to "eliminate" in their search for Zahra.

Police reported Monday that search dogs also detected the scent of human remains on two vehicles at the Bakers' home.

Several residents and family members have since come forward to portray Elisa Baker as an abusive stepmother who often beat Zahra and then tried to "cover up" the injuries by saying the girl fell. 

"I hate to say it, but I don’t feel good about this," said a family friend who spoke to FoxNews.com on condition of anonymity. "I really think Elisa had something to do with it." 

A MySpace page that appears to belong to Elisa Baker may also reveal disturbing details in the case.

The page, which is registered to user "gothicfairy6668," includes a slideshow of family photos -- one showing Zahra with the caption, "The Dark Child lol" 

The user identifies herself as E'lesa and describes her mood as "crazy."

"We're all going to to HELL and I'm driving the bus," reads the caption on one image of a devil cartoon character. 

Adam Baker is from Australia, and met his current wife over the Internet, a family friend said. Zahra's mother lives outside the U.S. Elisa Baker has two daughters and a son from a previous marriage.

Adam Baker said in a TV interview on Monday that it was possible his wife could be involved in the disappearance. 

Officers discovered the ransom note Saturday on the windshield of Adam Baker's car when they came to investigate a yard fire at their home. The stepmother said she last saw Zahra sleeping in her room 12 hours before she was reported missing on Saturday -- though Hickory Police Chief Tom Adkins has indicated he doesn't believe the timeline.

At a vigil Wednesday night, about 150 people sang religious songs, held hands and called on each other to love their children and report signs of child abuse to authorities. The case has disturbed Hickory, a city of about 40,000, some 50 miles northwest of Charlotte.

David King, a deacon at East Hickory Baptist Church, said everyone is praying for her.

"Kids should be having fun. No one should have to go through what she did," he said. "This is just a tragedy."

The Associated Press contributed to this report