CHICAGO (CBS) — Chicago Public Schools officials will run new background checks by fall for thousands of employees who regularly work in schools, as part of the district’s ongoing response to a sex abuse scandal.

The district had already announced it would conduct periodic background checks for all employees, but now says it will re-check the backgrounds of “all adults who regularly work in schools” by the start of the next school year – including teachers, coaches, other CPS employees, volunteers, and vendors.

The recheck will cost the district approximately $2 million.

“Creating a safer school district for our students means doing everything possible to ensure our students are surrounded by trustworthy adults,” said CPS CEO Dr. Janice K. Jackson. “I want parents to have comfort that all of the adults in our schools will safeguard their children, and this is an important and necessary step toward rebuilding the faith and trust that our parents have in their school district.”

Any adult CPS employee, coach, volunteer, or vendor who does not submit to a new background check by the end of the summer won’t be allowed on school grounds.

The new background checks are part of the district’s response to an exhaustive Chicago Tribune investigation, which found police investigated 523 reports of rape or sexual abuse at city schools over a period of 10 years. The report also found CPS failed to protect abused students in more than 100 cases.

The Chicago Teachers Union said it supports the district’s new background check policy.

“Our union has been advised of CPS’ plans to re-run background checks of our members, as part of their effort to respond to their appalling failures to protect students from child abuse,” CTU Vice President Jesse Sharkey said.

The union said about 30 percent of its members will need to submit new fingerprint data for the re-check, because they were fingerprinted before 2012, when the district’s current background check vendor took over. Other CTU members’ fingerprints are already on file, and the district will run those prints again before the start of the new school year in the fall.

“CPS has assured us that this new round of background checks is designed explicitly to identify issues related to child safety concerns, and we will be on the alert for any effort to target members outside of the scope of this review,” Sharkey said.