During the proceedings, the judge charged her with six felony counts of aggravated assault and 10 counts of felony murder. Another child was hospitalized and is now in serious but stable condition.
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. She was identified as 9-year-old Diana Romero.
Gwinnett County police say the victims were stabbed to death.
When offered the choice to be appointed an attorney, Martinez said her attorneys are the people and her faith, according to her translator.
Neighbor Letty Perez tells CBS46 News that Martinez had recently lost her father and the family had only lived in the home for about a month after moving to Georgia from IL.
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.
CBS 19 reports that another neighbor, Pedro Ramirez said Martinez had seemed happy until the death of her father.
"I'm representing the people that's humble, that's hardworking, the people that suffer, the people that have a lot of charges so that they understand that everything is possible through God".
She is expected to appear in court again on Thursday, July 20 at 8:30 a.m. But, the Times tried to bury the hold, slipping it into one statement reading "She was also being held for Immigration and Customs Enforcement, officials said".
"This is a horrendous crime not only for the victims but for the extended family, neighbourhood and community". Their slain father was Martin Romero, 33, Pihera said.
Gwinnett County Police Cpl.
According to police, Martinez went on the stabbing spree against her own family in the middle of the night, around 2 a.m. and 4 a.m.
Police said Martinez has been "cooperative" with investigators, but the motive for the crimes is not being released.