Prosecutors believe Santiago Esparza helped hide 5-year-old Sierra Patino's body. Esparza is expected to be charged with tampering with evidence on Thursday.
Detectives say Sierra's mother, Priscilla Nicole Torres, wrapped the girl's body in a blanket and put her in a closet.
Police say Torres told them she was too scared to call 911 after her daughter died because she feared CPS involvement.
She allegedly said Sierra died from ingesting chemicals on Aug. 27, and her body had been kept in the closet ever since.
The Medical Examiner's Office is still working to figure out a cause of death.
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Torres was arrested and has been charged with felony tampering with evidence, a human corpse. Houston police have said more charges are possible.
According to information revealed in court on Thursday, Sierra started kindergarten on Aug. 21.
The next day, Torres allegedly said Sierra was sick and didn't go to school. By that time, Sierra was staying with her grandmother.
Torres and Sierra moved to Esparza's apartment on Aug. 22.
Prosecutors said Torres claimed the girl died on Aug. 27. On Aug. 30, they said the mother and boyfriend checked into a Jacinto City hotel. They then spent the weekend in Galveston before returning to Houston on Labor Day.
Officers were called around 2:30 p.m. Monday to the Quail Creek apartment complex at 7835 Grow Lane in northwest Houston.
When asked about a foul smell inside the apartment, the mother confessed the source of the odor was Sierra's body, according to police.
Firefighters who found the girl's body covered it from view, describing it as being in a state of decay, according to police.
Prosecutors say Torres gave multiple stories to investigators, and changed them several times.
Defense attorneys told ABC7's sister station KTRK that Torres is not responsible for her daughter's death.
She appeared in probable cause court on Tuesday, where her bond was set at $50,000.
Prosecutors wanted Torres' bond raised to $100,000, saying they consider her a flight risk.