San Francisco Unified School District Superintendent Maria Su has warned teachers not to delete records that could relate to a federal investigation into the district’s classroom practices.

In a Thursday email to staff, Su said the district was gathering documents for a Justice Department Title IX compliance review launched in June. She asked employees to help locate relevant materials and said those likely to hold pertinent information had already been told to preserve it.

The review is expected to examine how the district informs parents about the pronouns students use at school and whether parents can withdraw children from instruction they oppose. The department is also looking at bathroom and locker-room access and transgender athletes’ participation on girls’ teams.

Su’s message followed her appearance before a House committee nearly three months earlier, when school leaders were questioned about teaching on race, gender and identity.