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LAWRENCEVILLE, Ga. — A woman charged with killing four of her young children and her husband smiled and flashed a double thumbs up to news cameras during her first court appearance Friday in metro Atlanta before telling a judge she doesn’t want an attorney.

Also, an immigration official said the woman, who is from Mexico, entered the U.S. illegally.

Isabel Martinez, 33, appeared before Gwinnett County Magistrate Court 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.

As 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,” he said. “It’s really not a good idea, probably not to your benefit.”

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 “that we’re fighting for” and her faith.

“You are the hope of the world, each one of you,” she said in Spanish, appearing to address the news cameras. “It doesn’t matter what color you are because God loves us all.”

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

Meanwhile, U.S. Immigration and Customs Enforcement spokesman Bryan Cox said in an email Friday that Martinez — whom he identified as Maria Isabel Garduno-Martinez — is from Mexico and entered the country illegally. This is her first encounter with immigration authorities, and it’s not clear how long she has been in the U.S., Cox said.

Isabel Martinez gestures towards news cameras during her first court appearance on July 7, 2017, in Lawrenceville, Georgia. John Bazemore / AP

Local officials called the killings “horrendous.”

“What prompts a person to take the life of such innocent children and her spouse is something we may never understand,” Gwinnett County police said in a statement. “This is a horrendous crime not only for the victims but for the extended family, neighborhood and community.”

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.”

Flowers and stuffed toys left on the doorstep of a home where four children and their father were stabbed to death are shown on July 7, 2017, in Loganville, Georgia. John Bazemore / AP

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.

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 U.S. Immigration and Customs Enforcement.

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. Police said Romero and Isabel Martinez were married.

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.