(CNN) - Casey Anthony's frustration level with her parents, particularly her mother, was rising around the time her 2-year-old daughter disappeared, for reasons including that her mother was increasingly unable to watch the child so Casey could hang out with her friends, one of those friends testified Tuesday.

Amy Huizenga told jurors in Anthony's capital murder trial that the two previously were close friends and that Anthony complained frequently about her parents, particularly her mother. Anthony's relationship with her mother was "strained. It was hard. Her mom was continually agitated with her," Huizenga said. "I remember she told me her mom had told her she was an unfit mother. She was extremely upset about that."

But Anthony was agitated at her mother as well, as she had to cancel plans "fairly frequently" because she had no one to watch her daughter, Huizenga testified. It was happening more frequently during the spring of 2008, Huizenga said, and the "frustration was greater."

In late June, Anthony told her that she was keeping Caylee away from her parents, as they were having marital problems and were considering divorce, and "she wanted to keep Caylee out of the drama."

But actually, by late June, Caylee was missing. The last time the little girl was seen was June 16, and she was not reported missing until July 15 by Cindy Anthony, Casey Anthony's mother.

Casey Anthony, 25, is charged with seven counts in Caylee's death, including first-degree murder, aggravated child abuse and misleading police. If convicted, she could face the death penalty.

She has pleaded not guilty and denied harming her daughter or having anything to do with the little girl's disappearance or death. Defense attorney Jose Baez has said that once all the facts were known, it will become clear his client is innocent.

Caylee's skeletal remains were found in December 2008 in a wooded field not far from the home of Casey Anthony's parents, George and Cindy Anthony.