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(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.

Earlier, jurors heard an obscenity-strewn phone conversation Casey Anthony made from jail just after her arrest, in which she lamented that no one was listening to her, denied knowing what had happened to Caylee and said authorities weren't trying hard enough to find the nanny she claimed had kidnapped the child.

Also Tuesday, jurors heard a recording of the call made to her parents' home on July 16, 2008, the day after Caylee was reported missing.

In the call, Anthony speaks to her mother, her brother and her friend Kristina Chester. She asks her brother to give her the phone number of her then-boyfriend, Tony Lazzaro.

A tearful Chester tries to get answers out of Anthony regarding Caylee's whereabouts. The child had last been seen June 16, a month earlier.

"I got arrested on a f---ing whim today," Anthony tells Chester on the call, "because they're blaming me for stuff that I would never do, that I didn't do.

"They're twisting stuff," Anthony says. "They've already said they're going to pin this on me if they don't find Caylee. They've already said that."

"Casey," Chester says later in the call. "Your daughter, your flesh and blood, your baby." But Anthony cuts her off, saying, "Put my brother back on the phone. I don't want to get into this with you. ... I haven't slept in four days."

Asked by Chester during the call why she isn't crying and upset, Anthony said on the recording, "I have to stay composed to talk to detectives. ... I can't sit here and be crying every two seconds like I want to."

Jurors also heard a call to the Orange County, Florida, Sheriff's Office made July 15 by a hysterical Cindy Anthony, reporting her granddaughter missing. The call was made, Cindy Anthony testified, after her daughter told her she had not seen Caylee for weeks.

Her daughter also was absent, moving out of her parents' home with little explanation and giving various explanations of where she was, where Caylee was and why Caylee was unavailable for her grandparents to see or speak to. "There was always a reason I missed her," Cindy Anthony said.

She testified that she made her 911 call -- her third to police that day -- after she and her son, Lee, had confronted Casey Anthony, who admitted that Caylee had been missing for a month and that she believed the nanny, who she identified as Zenaida Fernandez-Gonzalez, had kidnapped her.

"My daughter's been missing for 31 days," Casey Anthony tells the dispatcher on the recording after her mother put her on the phone. "I know who has her. I've tried to contact her. I actually received a phone call today. I got to speak to my daughter for about a minute."

"Why didn't you call 31 days ago?" the Orange County sheriff's dispatcher asks on the recording.

"I've been looking for her," Casey Anthony replied, "and have gone through other resources to find her, which was stupid."

But Casey Anthony was not looking for her daughter in the month she was missing, despite her claim to police, according to prosecutors and testimony offered in her trial. Instead, she was staying with her boyfriend, spending time in Orlando with numerous friends, attending parties, going shopping and hitting nightclubs, including participating in a "hot body" contest. Her former boyfriend, her friends and acquaintances have all testified that she did not mention her daughter being missing during that time.

As call of the 911 call was played, Cindy Anthony put her head down on the witness stand and sobbed.

Authorities were never able to find the nanny. They did find a woman named Zenaida "Zanny" Gonzalez, who denied ever meeting Casey Anthony or Caylee and later sued for defamation.

Told by Chester in the phone call that authorities can't find Gonzalez, Anthony says, "Nobody's f---ing listening to anything I'm saying. ... They can't find her in the Florida database (of driver's licenses). She's not just from Florida."

Under cross-examination, Cindy Anthony testified that her daughter was a good mother to Caylee.

"Casey was a very loving, very caring mother," she said. "She had a very easy, very quick maternal instinct that was very evident as soon as Caylee was born. She reminded me of myself when my kids were born, and just how natural she was with Caylee."

The little girl adored her mother, she testified, and followed her nearly everywhere. As Cindy Anthony testified, Casey Anthony smiled and wiped her eyes.

Cindy Anthony also testified that her daughter had been telling her about Gonzalez along with numerous other people -- a boyfriend, a co-worker and a man named Eric Baker, whom she believed to be Caylee's father -- for years before Caylee went missing. At the time, she said, she never had a reason to believe those people were fictitious. "I just found out they were imaginary people," she testified.

She said her and her husband's efforts to find Gonzalez had continued up to six weeks before the trial started, taking them to places including New York and California.

Earlier, Cindy Anthony testified that on July 15, George Anthony picked up a certified letter from a tow yard, which said that Casey Anthony's Pontiac Sunfire -- registered to her parents -- had been there for a couple of weeks.

Cindy Anthony testified that her daughter had told her that the car was with her in Jacksonville, Florida, and she called her and told her "she had a lot of explaining to do." She asked her to come home.

After George Anthony drove the car home from the wrecker yard, Cindy Anthony, a nurse, said she smelled the car and asked, "What died?" She testified that she knows what human decomposition smells like but said it was just an expression and that she didn't really believe someone had died or a body had decomposed in the car. She said that at the time, she was satisfied that the smell was some garbage her husband said he found in the trunk.

But "the smell in the car was like something I had never -- it was pretty strong," she said.

After her husband left for work, Cindy Anthony said, she retrieved her daughter's purse from the car, along with a doll. She broke into tears as she described finding the doll in Caylee's car seat, "like it was sitting where Caylee would have sat."

She tearfully recalled putting the doll on an ice chest in the garage and wiping its face and hands with a disinfecting wipe, then spraying its body and the interior of the car with Febreze, a commercial substance that helps eliminate odor. She said she also put a dryer sheet in the car.

She acknowledged telling authorities in her frantic 911 call that her daughter's car smelled "like there's been a body" but told Baez she said that in an effort to get deputies to arrive faster.

Prosecutors allege that Anthony used chloroform on her daughter and then suffocated her by putting duct tape over her nose and mouth.

Anthony's defense has claimed that the little girl drowned in the her grandparents' pool on June 16, the day she was last seen, and that Casey Anthony and her father panicked and kept the death a secret. George Anthony has denied that claim in testimony.

Casey Anthony's defense attorney explains her behavior in June and July 2008 by saying she had been sexually abused as a child by her father -- and, to a lesser extent, her brother -- and was taught from a young age to hide her pain. George Anthony has also denied abusing his daughter in previous testimony.

Cindy Anthony testified that her daughter was not answering her phone after the car was picked up July 15, so she contacted Huizenga, picking her up at a mall and asking her to take her to her daughter. She was directed to Lazzaro's apartment.

On the stand Tuesday, Huizenga recalled the tense confrontation that followed. Cindy Anthony was demanding to see Caylee, she recalled, and Casey Anthony said she was with her nanny. It was "a massive explosion of mother and daughter," Huizenga said.

Under cross-examination, Cindy Anthony testified that she and her granddaughter swam together on June 15, the day before Caylee was last seen. Asked whether she was certain she had removed the ladder from the above-ground pool, she said, "as certain as I can be. I do recall taking the ladder down." But she acknowledged mentioning to a co-worker the next day that she thought someone had been swimming in her pool, as she had found the ladder up and the gate open.

The case has drawn attention across the nation and beyond. On Tuesday morning, about 250 people were standing in line for a seat in the courtroom, a record so far, said In Session producer Grace Wong. Sixty of them were seated, more than the usual 48, as fewer media were attending, Wong said.

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