The House Oversight Committee is demanding documents related to government contracts with companies that detain or house thousands of immigrants.

Rep. Elijah E. Cummings, the chairman of the Committee on Oversight and Reform, and Rep. Jamie Raskin, the chairman of the Subcommittee on Civil Rights and Civil Liberties, sent letters to two for-profit contractors operating Immigration and Customs Enforcement (ICE) detention centers, as well as another company that runs the nation's largest holding facility for unaccompanied migrant children. The congressmen also sent letters seeking similar information from ICE and the U.S. Department of Health and Human Services, which oversees care for unaccompanied migrant children.

The move comes amid a groundswell of public outrage following reports of abuse and a rash of migrant deaths in government custody.

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"The Committee is investigating the Trump Administration's rapidly increasing use of for-profit contractors to detain tens of thousands of immigrants, including a troubling series of reports of health and safety violations and the dramatically escalating and seemingly unchecked costs to U.S. taxpayers for these contracts," Cummings and Raskin wrote in their letters.

The lawmakers cited claims of abuse and inadequate living conditions in their letters to the chief executives of CoreCivic, Geo Group, Inc., and DC Capital Partners, LLC. CoreCivic and Geo Group are each paid hundreds of millions of dollars to operate detention centers for ICE. DC Capital Partners is an investment firm that owns Caliburn International, the parent corporation of the company that operates a massive unaccompanied children shelter in Homestead, Florida.

The letters to DC Capital President Thomas Campbell and HHS Secretary Alexander Azar note that the company running the Homestead location has received government contracts totaling more than $545 million. The letters point to a series of sexual abuse complaints at the facility and cite a CBS News report documenting the rapid hiring of employees who were granted a government waiver allowing them to bypass Florida's child abuse and neglect background check system.

Another CBS News report, revealing that former White House Chief of Staff John Kelly joined Caliburn's Board of Directors, is also cited. Before joining the White House, Kelly was also on DC Capital's board. The investment firm bought the company operating the Homestead facility in 2018 while Kelly worked at the White House, and its unaccompanied children operation tripled in size before he left.

The House Judiciary Committee authorized a subpoena for Kelly Thursday, related to his both his work for Caliburn and his role in determining federal immigration policy.

A spokesperson for Caliburn said in a statement to CBS News that the company welcomes the investigation "as a chance to tell our story and dispel misapprehensions about the critical work we do taking care of the teenagers at the Homestead temporary emergency care shelter until they can be placed in a safe home during this unprecedented surge of unaccompanied minors entering the U.S."

The letters to CoreCivic, Geo Group and ICE note that the companies are being paid substantial sums to run facilities that have been repeatedly criticized by the Department of Homeland Security's Inspector General for dangerous conditions. The letters point to at least 25 deaths in ICE facilities since 2017.

Both companies said in statements emailed to CBS News that they are reviewing the letters.

Geo Group noted in its statement that "for more than 30 years, GEO's processing centers have been subject to independent oversight, including full-time, on-site government monitors."

"We are committed to transparency, and providing the safest and most humane care possible for those in our 14 ICE processing centers is our top priority," the company said.

"It's critical to understand that CoreCivic has a 35-year track record of working with both Democrat and Republican administrations to help solve the very types of crises we are now seeing on our southern border," said CoreCivic spokesperson Amanda Gilchrist. The statement included a bullet-pointed set of "key facts about our company" that included a claim that it has never housed unaccompanied migrant children.

CoreCivic was previously known as Corrections Corporation of America until changing its name in 2016. In the 1980s, Corrections Corporation of America operated an immigration detention center in Texas that was included in a landmark court case about unaccompanied migrant children. The case included allegations by a 16-year-old girl of strip and vaginal searches by guards at the facility. The allegations were not proven and the case was settled.

That case led to the Flores Agreement, which set the nation's laws governing how unaccompanied children must be treated by the government.

The company said in statements to CBS News that it has never contracted to house unaccompanied migrant children. "It's unlikely that (federal immigration officials were) able to properly ascertain her age" at the time, the company said. The Flores case "was about INS practices at the time" and not specifically about the Texas detention center, the company said.

"CoreCivic does not operate facilities for the purpose of housing unaccompanied minors," Gilchrist said.

Editor's note: This story has been updated to clarify the involvement of Corrections Corporation of America in the Flores litigation.