SAN ANTONIO -- The Gonzales County Sherrif confirmed Sunday that foster parents of an 8-year-old girl who was found dead last week were charged with injury to a child.

Betty and Steve Ramirez, the girl's uncle and aunt, were arrested last week after 8-year-old Crystal was found dead.

Gonzales County Sheriff Glen Sachtleben said Crystal's death remains a mystery, but the investigation is ongoing and is too important to rush.

Crystal's sister and baby brother were also living with the Ramirez's.

Crystal's mother Teresa Camarillo blames the Ramirez's for her daughter's death.

"I thought foster parents were supposed to protect them, not hurt them," Camarillo said. "I want them to pay for what they've done. They hurt her a baby that can't defend herself."

Camarillo lost custody of her children five years ago after she admitted to selling and using drugs. She said she hasn't seen Crystal since then.

Camarillo said she is not allowed to come to a private funeral service for her daughter because she lost custody of her.

Child Protective Services and the Texas Rangers are assisting with the investigation.

Camarillo said more information about the case will be released on Monday.

Betty Ramirez is being held on a $100,000 bond and Steve Ramirez is being held on a $150,000 bond.