Department of Homeland Security Secretary Markywayne Mullin admitted to lawmakers that his predecessor “maybe” didn’t complete “due diligence” when purchasing 11 warehouses to convert into detention centers around the country.

Mullin, who took over DHS in March after President Donald Trump fired former Secretary Kristi Noem, told lawmakers on the House Appropriations Subcommittee on Homeland Security Thursday that he was “evaluating” the purchases totaling roughly $1 billion.

“There was some due diligence that maybe wasn’t actually checked off. And so, what you’re saying is not wrong,” Mullin told Democratic Rep. Veronica Escobar of Texas after she raised concerns about the feasibility of one warehouse location.

For months, reports have accused Noem of rushing to purchase and overpaying for warehouses to turn into immigration detention centers to support the president’s mass deportation agenda. Some lawmakers have questioned whether certain locations had the infrastructure to support humans. Local officials have expressed outrage at the department for buying warehouses without any warning.

“There’s some that just, quite frankly, probably won’t work,” Mullin admitted.

Mullin’s testimony was a rare admission from a top Trump administration official that an immigration-related policy was not thoughtfully analyzed before being rolled out.

The Washington Post was the first to report on Mullin’s testimony.

Though DHS has faced similar accusations for more than a year, officials have been reluctant to admit to the problem. The department’s internal watchdog is reportedly conducting a review of the warehouse purchases as well as Noem’s contracting process.

Mullin told lawmakers that the department has “issues” with detention center bed space but that they were “going through and re-evaluating every one of them to be the best possible outcome for our mission inside of DHS.”

Last year, documents revealed DHS and Immigration and Customs Enforcement were dedicating $38 billion toward buying and converting buildings into smaller temporary detention centers to hold thousands of detained immigrants before moving them to larger facilities.

Over the course of her 14-month tenure, Noem approved the acquisition of roughly 11 warehouses that the department planned to turn into temporary holding facilities. However, the Wall Street Journal reported that Noem pressured officials to open facilities quickly, despite the warehouses not being properly zoned for detention and without working plumbing.

Many of the warehouses also faced legal challenges from locals.

One warehouse, located in Roxbury, New Jersey, was purchased for $129 million in February but remained empty after local officials successfully petitioned a judge to temporarily halt the project until an environmental review was conducted. In Salt Lake City, Utah, officials have challenged the purchase of a $145.4 million warehouse, which currently sits unused.

Now, DHS is planning to get rid of those two warehouses, the New York Times reported last week.

The Arizona attorney general sued ICE in April, in an attempt to stop officials from turning a warehouse in Surprise, purchased for $70 million, into a detention facility. Though DHS is still moving forward with its acquisition, the New York Times said.