Daniel Shepard, 62, retired from Westminster High School, where he met the alleged victim two years ago. His wife, Gay Davidson-Shepard, 59, is a teacher at Mesa View Middle School, where students are returned from spring break on Monday.
The two are accused of having a sexual relationship with the same underage student.
A spokeswoman for prosecutors told ABC News that more possible victims have now come forward.
The Shepards were arrested last week and were set to be formally arraigned in May.