Portland-area teaching assistant arrested on child sex abuse charges

According to the Washington County Sheriff’s Office, in April 2023 it opened an investigation after learning a special education teaching assistant in the Hillsboro School District may have sexually assaulted a student away from school property.

Detectives with the Violent Crimes Unit were assigned and learned that 22-year-old Yessenia Manriquez Casillas, who lives in Beaverton, was an employee of the Hillsboro School District and worked at Century High School.

Manriquez Casillas allegedly picked up the student at a celebration and then sexually abused the person.

In June, a Washington County grand jury heard evidence on the case and issued an indictment for Manriquez Casillas’ arrest.

On June 14, deputies with the Sheriff’s Office Criminal Apprehension Team arrested Manriquez Casillas at her home and booked her into the Washington County Jail on four counts of second-degree sexual abuse.

The school district placed Manriquez Casillas on administrative leave after law enforcement notified them of the alleged abuse and she was fired on April 7.

On Thursday, the school district sent a letter to students, staff, and families that said, “Because the safety of our students is our highest priority, we are devastated by this information and its impact on the student, their family, and any other students that may have been involved. We do appreciate and continue to encourage students to report inappropriate behavior to a trusted adult immediately so that action can be taken.”

Detectives from the sheriff’s office are concerned there might be more victims and have asked that anyone with information about the investigation should contact them at 503-846-2700.