"Yes, they see me as a big sister, but for me, I really see them as my girls," she said.
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At just 19, Martinez has been forced into the role of mother to 14-year-old Daniela and 11-year-old Miranda. Both girls have autism, she says.
She remembers some happy times with their parents, but most of them were overshadowed by the dark ones.
"Hitting her, causing a lot of pain, making me feel bad," recalled Martinez. "It was a lot of things."
Jose Martinez-Espinosa, their father, has been on the run since last November. He is charged with murder, accused of shooting their mother, Ninfa Griselda Mancillas, multiple times at their southeast Houston home.
Martinez says her mother was trying to leave him. The youngest girl found their mother dead.
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"She was so scared. She was crying. I didn't know what to do," said Martinez.
In the five months since, Martinez has learned a lot about life and a lot about herself.
"I may not have my mom, but I know she's taking care of us."
She is in her second semester at Houston Community College, and hopes to be a federal agent one day.
How she is going to pay for it while supporting her sisters is another issue. She's asking for help from the community.
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Her mother would want her to stay in school. She wants people, especially her father, to see the consequences of domestic violence.
"I want to reach out to him to make him understand how bad his actions caused lot of issues, and I just want him to turn himself in."
Houston police say it's possible Martinez has fled to Mexico. Anyone with information on his whereabouts is asked to contact Crime Stoppers.
A GoFundMe has been set up to help the 19-year-old and her sisters.
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