A longtime educator with the Northside Independent School District (NISD) has been arrested following disturbing allegations of sexual assault involving a minor. Cecilia Mueller, 46, was taken into custody on Monday, April 27, 2026, after a former student came forward with details of abuse that allegedly took place during the 2016-17 school year.
The investigation began when the victim, now 20 years old, reported the incidents to the San Antonio Police Department. According to the police report, the abuse occurred while the victim was a 10-year-old student in Mueller’s fifth-grade class at Lewis Elementary School.
The victim described a "grooming" process where Mueller singled out certain students as her "favorites," seating them together and subjecting them to inappropriate conversations about their personal lives and romantic interests.
The victim alleged that Mueller engaged in sexual acts with him inside a classroom closet, once even doing so while her own young child was present in the room. The report also details "depraved" lunchtime gatherings where Mueller allegedly played explicit music videos and pornography for the children.
Furthermore, Mueller is accused of orchestrating games of "Truth or Dare," encouraging the fifth graders to kiss one another while warning them to keep the meetings a secret from their parents.
Mueller, who had been with the district since 2007, transferred from Lewis Elementary to Henderson Elementary in 2019. Following her arrest, NISD officials placed her on administrative leave and confirmed they are cooperating fully with law enforcement. Mueller has been charged with continuous sexual assault of a child, a first-degree felony.
Authorities believe there may be additional victims given Mueller’s nearly 20-year career in the classroom. The San Antonio Police Department is urging anyone with information or who may have had similar experiences with Mueller to contact their Special Victims Unit.