The remains, which were found about quarter-mile from the home Caylee Anthony shared with her mother and grandparents, have not been identified. But a lawyer for Cindy and George Anthony, Caylee's grandparents, said they were bracing for the worst.
"They are devastated by the findings and devastated by the fact that this may be their granddaughter," said Brad Conway.
The two-year-old was last seen in June by her grandparents but and was reported missing in July. Casey Anthony was charged with first-degree murder in October. She has pleaded not guilty.
A water utility worker discovered a child's skull Thursday. FBI agents spent four days scouring the wooded area, removing brush and sifting through mounds of dirt, looking for more clues.
Police sources said the skull, covered with cloth and found inside a garbage bag, still had duct tape attached to the mouth.
DNA results are not expected for another week, but police said the hair color and size of the body are consistent with Caylee Anthony's.
An Orange County Sheriff's Office spokesman said today that "significant finds," in addition to the skull, had been made in the search over the weekend, but declined to elaborate.
After executing a search warrant, investigators removed bags of evidence from the Anthony's home, including a pillow, a vacuum cleaner, pesticides and pool chemicals.
Casey Anthony's defense team, including forensics expert Henry Lee, who worked on the O.J. Simpson and Jon Benet Ramsey cases, had been shut out of the crime scene, according to her attorney.
"We should be able to observe even if not from a distance or have qualified people in there," attorney Jose Baez said.
The resolution of the case will rely heavily on forensic evidence, said Lawrence Kobilinsky, a professor of forensic science at the John Jay College of Criminal Justice in New York City and a member of Casey Anthony's defense team.
"Both the duct tape and the bag are critical pieces of evidence. The duct tape, especially on the adhesive side, can reveal fingerprints, perhaps trace evidence, fiber, soil," Kobilinsky said. "Certainly for comparison purposes, examining this type of substance found in the Anthony home, I think this is what law enforcement is going to be looking into."
The family is "devastated" by the discovery of the remains, said Conway. He said they were continuing to support their daughter.
Caylee's uncle, Lee Anthony, the brother of Casey Anthony, dismantled a memorial of pictures, stuffed animals and flowers in the family's yard Saturday and warned reporters, "Don't follow me into the yard or I'll call law enforcement."
Scientists found evidence of body decomposition and traces of chloroform in Casey Anthony's car trunk, according to forensics reports released in October.
Lab reports from the FBI found that a hair strand in the trunk showed "characteristics of apparent decomposition." The hair is "microscopically similar" to hair strands found on Caylee's brush, but the report said it could not conclusively say the hair in the trunk came from the missing girl.