The State Attorney's Office released interviews with Shirley Plesea and others on Anthony's behavior, The Orlando (Fla.) Sentinel reported.
Plesea said that Anthony stole so much money from her parents, George and Cindy Anthony, that they were worried about losing their house. Plesea is Cindy Anthony's mother.
Cindy Anthony's changing stories after her granddaughter was reported missing were caused by denial, Plesea said.
"She's out of control for one reason. If she doesn't believe Casey then Caylee's dead," Plesea said. "If she could not believe Casey, believe in Casey, she'd have to accept the fact that … Caylee might be dead, or would be dead, or whatever."
Casey Anthony was charged with the murder of her daughter before the toddler's skeletal remains were found in a wooded swamp near George and Cindy Anthony's home in Orlando.
Plesea said that Anthony also stole from her. The first time, she said, her granddaughter forged a check that she used to pay for a party for Caylee's second birthday.