A warrant was issued for 30-year-old Santiago Esparza, the boyfriend of Sierra's mother Priscilla Nicole Torres.
Authorities filed a tampering with evidence charge against Esparza, who they believe helped Torres hide the body of the 5-year-old girl.
UPDATE #4:— Houston Police (@houstonpolice) September 6, 2019
WANTED: A warrant for the same felony charge of tampering with evidence is now filed against Santiago Esparza, Jr., 30. This is a 2016 booking photo of Esparza. If you know his whereabouts, please call HPD Homicide 713-308-3600 or @CrimeStopHOU 713-222-TIPS. #hounews pic.twitter.com/QEBxP8MjVv
Detectives say 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 until she was discovered on Labor Day.
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. At 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.
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 ABC13 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.
If released from the Harris County jail, they fear Esparza might hide her in Mexico.
They accuse him of being a documented gang member with a group known as Tango Blast.
"Tango Blast has an extensive network in Mexico and could hide the defendant to hinder her prosecution," read the state's motion for high bond.
Esparza has faced a number of charges before for endangering a child, assault of a family member, evading, assault bodily injury and injuring a child.
In 2015, he was sentenced to four years of probation for endangering a child.
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