A number of high-ranking Democratic lawmakers are demanding Tom Homan, President Donald Trump’s border czar, divulge more details on his past ties with the detention services provider Geo Group, which has secured lucrative government contracts amid Trump’s mass deportation policy.

Before being tapped by Trump, Homan served as a paid consultant for GEO Group, which in February was awarded a $1 billion, 15-year contract with Immigration and Customs Enforcement to house migrants awaiting deportation.

Following his appointment, Homan brought on his former colleague at Geo Group, David Venturella, as ICE’s “No. 2 official” overseeing contracts for detention centers, according to The Washington Post, sparking a demand for answers from Reps. Jamie Raskin (D-MD), Jasmine Crockett (D-TX) and Pramila Jayapal (D-WA).

Now, Democratic lawmakers are demanding answers, and have sent a letter detailing their demands on Monday, which they shared with The Washington Post.

“Your past work as a paid consultant for Geo Group and your involvement in the hiring of Mr. Venturella raise serious concerns about potential conflicts of interest in this arrangement,” reads the joint letter, sent to Homan on Monday.

“In light of these grave concerns and your past work for Geo Group, you may have an actual conflict of interest – and certainly the appearance of one – if you are participating in or influencing agency decisions or actions that could affect the spending of hundreds of millions or even billions of dollars with your former client.”

In the letter, the lawmakers demand that Homan provide to the House Judiciary Committee further details of his past and current relationship with Geo Group, and by 5 p.m. on Sept. 8. Among the lawmakers’ demands include a full accounting of all financial benefits Homan received from Geo Group, and all communications between Homan and Venturella.

The lawmakers also highlighted the dangerous conditions at many Geo Group detention centers as cause for concern, suggesting that the lucrative government contracts they secured were not done without bias or favoritism.

“The increasing reliance on Geo Group by ICE is particularly troubling given the well-documented history of abuse, mismanagement, and neglect within the company’s facilities,” the letter reads. “Over the years, there have been reports of Geo Group facilities refusing or failing to provide essential medical care, as well as the presence of dangerous and unsanitary conditions and ‘abysmal’ food within detention centers.”