On Tuesday, Priscilla Nicole Torres was arrested in connection to the child's death.
Police say the 5-year-old's body was hidden in the closet for nearly a week.
Child Protective Services confirms the child's name is Sierra Patino.
Officers were called around 2:30 p.m. Monday to the Quail Creek apartment complex at 7835 Grow Lane in northwest Houston.
Police say family members came to the apartment earlier Monday to check on a 5-year-old girl, who hadn't been seen for some time.
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When the visitors asked about a foul smell inside the apartment, the mother confessed the source of the odor was Sierra's body, according to police.
Officers said she claimed the child had died from ingesting chemicals on Aug. 27. Sierra's body had been kept in the closet ever since.
Firefighters who found the girl's body covered it from view, describing it as being in a state of decay, according to police.
"It's very troubling," said HPD Lt. Larry Crowson. "No matter how the child died, you know, whether it's an accidental or intentional death, for a body to be in a closet for several days, that's just unthinkable."
Investigators are now trying to see whether Sierra's death is consistent with the mother's statement to police.
An autopsy will determine whether her death was accidental or intentional, and is expected to shed light on what chemical she may have ingested.
The mother's live in boyfriend will also be questioned as part of the investigation, according to CPS. They say this is standard procedure for any case.