The closure of 23 DC Public Schools cost the city nearly $40 million, or four times the $9.7 million initially reported, according to a new report by the D.C. auditor.

The extra $30 million includes the demolition of two campuses, transportation of students, moving and relocating expenses, paychecks for guards to watch the empty schools and lost value of the buildings.

The closings were in 2008, under a different mayor -- Adrian Fenty -- and a different chancellor -- Michelle Rhee. But Mayor Vincent Gray and school leaders have been clear in recent months that another round of school closures is imminent, as many of the city's 125 schools are significantly underenrolled; at least 40 schools, generally low-performing, have 300 or fewer students. The idea is that reducing facilities costs allows the city to spend more money directly on student programs.

But according to a report by D.C. Auditor Yolanda Branche's office, the actual cost to the city of shuttering the 23 schools was steep: $39.5 million.

"As this report addresses school closures from 2007 under the previous administration, any future decisions will require a thorough and updated analysis," Deputy Mayor for Education De'Shawn Wright said in an email.

In addition to the $9.7 million in inventory, relocation and storage costs that city officials had previously cited, the auditor identifies another $3.1 million in moving expenses. To demolish Gage-Eckington Elementary School in 2009 and Bruce-Monroe Elementary in 2010, the city spent another $3.3 million. To patrol closed schools in fiscal 2009, the city paid D.C. Protective Services $38,870. And to transport displaced students to alternate schools, the price tag was $1.5 million. Those costs add up to an extra $8 million.

The biggest expense cited by Branche, however, is capital asset "impairment losses" of $21.8 million. According to the auditor, eight of the shuttered buildings lost much of their worth on the market when they stopped being schools. For example, Brookland's Slowe Elementary School lost $2.7 million in value in 2008.

It's not clear how much D.C. saved by closing the 23 schools. Brian Hanlon, the acting director of the Department of General Services, did not respond to emails seeking comment. Wright and his staff declined to comment beyond a brief emailed statement.

The deputy mayor for education is responsible for school facilities and has taken the lead on the upcoming closures. In January, Wright released a study recommending that 36 DC Public Schools campuses be closed or turned around, possibly as charter schools. Ten charter schools were recommended for closure.

David Pickens, executive director of DC School Reform Now, said the cost of closing schools didn't matter if it improved students' education. But although test scores have inched up in recent years, Pickens said it hasn't been enough progress to justify the cost of the closures.

"I don't think we have seen a return on our investment," he said. "I don't think we've seen that, and certainly for the amount of money that was spent, we should have seen more."