ATLANTA -- A woman charged with killing four of her young children and their father smiled and flashed a double thumbs up to news cameras during her first court appearance Friday before telling a judge she doesn't want an attorney.

Isabel Martinez, 33, appeared before Gwinnett County Magistrate Judge Michael Thorpe a day after police said she stabbed the five to death and seriously injured another child at her home outside Atlanta. The injured child, a 9-year-old girl, survived but remained hospitalized with injuries police described as serious.

Before the hearing began, Martinez sat with other inmates and struck poses for cameras - smiling, giving the thumbs up, putting her hands in a prayer position and spreading her arms out wide. At one point she got off the bench and knelt before the cameras before a bailiff warned her to sit back down, reports CBS affiliate WGCL.

As Judge Thorpe listed the charges against her - five counts of malice murder, five counts of murder, and six counts of aggravated assault - Martinez smiled, shook her head "no" and wagged her finger at him. The judge advised her sharply not to perform for the cameras.

"Ma'am, I'm going to caution you to cut out the display for the cameras. It's really not a good idea and probably not to your benefit," Thorpe said.

When Thorpe informed her of her right to have an attorney, she said through a Spanish-language interpreter, that she doesn't want one. She later added that her attorney will always be the people and her faith.

She said through the interpreter that "we are all God's people" and "God love us all," reports WGCL.

Thorpe advised Martinez to hire a lawyer or to allow one to be appointed for her.

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Psychologists and others who study cases of mothers accused of killing their children say it's not as uncommon as people might believe. But media coverage often focuses on dramatic cases, such as Andrea Yates who was found not guilty by reason of insanity for the 2001 drowning deaths of her five children in her suburban Houston home.

Other cases get less attention, as when a woman kills a newborn or in children's deaths blamed on neglect, said Cheryl Meyer, co-author of two books on mothers who have killed children based on about 1,000 cases during the 1990s.

That amounts to roughly one death every three days. If anything, the total based on media reports at the time underestimates the reality, said Meyer, a psychology professor at Wright State University in Ohio.

In cases when mothers kill intentionally, Meyer said there is often another influence, such as mental health issues, postpartum depression or the loss of a close loved one.

"We like to classify these women as pariahs, that they aren't at all like us," Meyer said. "I found that was not the case."

Some neighbors in the small, largely Hispanic neighborhood in Loganville, about 30 miles (48 kilometers) east of Atlanta, said they had no clue anything was amiss in the home until police mobbed the scene Thursday morning. The neighbors said the Spanish-speaking family had moved to the community recently, and their children seemed happy playing with other neighborhood kids.

Jim Hollandsworth, spokesman at The Path Project, a nonprofit organization that runs an after-school program that the family's children participated in, said the family had been in the community for a few months. While the children spoke English as a second language, he said, they were fluent.

"It's awful. It's devastating. Everyone is in complete shock," he said. "The kids were engaged in what we're doing. They were happy. They were fantastic kids with a bright future."

Victoria Nievs said Martinez had recently suffered the death of her father.

Gwinnett County Police Cpl. Michele Pihera confirmed that the 911 call came from a woman who was inside the home at 4:47 a.m. Thursday to report a stabbing. Police believe Martinez made that call.

Pihera said the caller was speaking Spanish, which initially made it difficult for 911 operators to communicate with her. The county sheriff's office said Martinez is on a hold for US Immigration and Customs Enforcement but didn't provide further details.

The hospitalized girl, Diana Romero, was in serious but stable condition Thursday evening, police said.

The four children killed were identified as Isabela Martinez, 10; Dacota Romero, 7; Dillan Romero, 4; and Axel Romero, 2. Their slain father was Martin Romero, 33, Pihera said.

Early indications are that a knife was used to attack the five, though a medical examiner will make the final determination about the cause of death, she said.

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