OMAHA, Neb. -- A former Omaha Public Schools security guard was supposed to appear for a preliminary hearing in Sarpy County Tuesday. 

Instead, he waived that right and now the case will go to trial. 23-year-old Carlos Ramirez is facing first and third-degree sexual assault of a child charges. 

He was arrested last month after students reported that a security guard may have had sexual contact with a student on school property. 

The police report says the incident happened after school hours in a portable classroom.

A trial date has not yet been scheduled.