A lawmaker is calling for an investigation in the wake of an ABC News report that highlighted the deaths of two migrants who fell ill while being held in U.S. detention facilities.

The families of Mariee Juarez, a Guatemalan toddler who died in 2018, and Gerardo Cruz, a 52-year-old Mexican father of six who died in 2016, have both made legal claims alleging that they received improper or insufficient medical care while in custody.

In December, Rep. Juan Vargas, a Democrat from California whose district includes the Otay Mesa Detention Center where Cruz was detained before he died, sent letters to the Department of Homeland Security (DHS), which oversees all immigrant detention centers; Immigration and Customs Enforcement (ICE), which provides all medical care at the detention centers through ICE Health Services and CoreCivic, Inc., the Nashville-based private company that operates the Otay Mesa Detention Center. The letter specifically references Cruz’s death and requests that DHS, ICE and CoreCivic “reveal their guidelines for the medical treatment of immigrants in detention centers.”

“The current systems in place are failing and people, including children, are dying,” Vargas told ABC News. “Everyone deserves to be treated with dignity and have access to proper medical care.”

But after several weeks of waiting, Vargas says has not received a response from either the federal agencies or the private company, prompting him to call for an independent congressional investigation.

“To date, I have not received responses and refuse to accept silence from these federal agencies and organizations,” Vargas told ABC News. “I have urged my colleagues on the House Committee on Homeland Security to hold a formal hearing. We must fully investigate the circumstances that led to people losing their lives while under federal custody.”

Rep. Juan Vargas, D-Calif., walks down the House steps at the Capitol after a series of votes on repeal and replace of Obamacare, May 4, 2017.(Bill Clark/CQ Roll Call/Getty Images ) Rep. Juan Vargas, D-Calif., walks down the House steps at the Capitol after a series of votes on repeal and replace of Obamacare, May 4, 2017.

A spokesperson for the House Committee on Homeland Security, of which Vargas is not a member, told ABC News that he expects the issue to be raised when Department of Homeland Security Secretary Kirstjen Nielsen appears before the committee in March.

Juarez died several weeks after developing a respiratory infection while detained at a CoreCivic-run family detention center in Dilley, Texas. Medical records obtained by ABC News show there was no indication Mariee was sick when she entered the facility, but she soon developed a respiratory infection that her mother Yazmin says was inadequately treated for nearly two weeks at the detention center’s medical clinic, run by ICE Health Services.

Her family filed an administrative wrongful death claim, a precursor to a lawsuit, against DHS, ICE and other federal agencies, as well as the City of Eloy, alleging that "Mariee died because the medical care she received at the Dilley detention facility was woefully inadequate, neglectful, and substandard."

Cruz died in a nearby hospital after falling seriously ill while detained at a CoreCivic-run detention center near San Diego, California. Medical records show that Cruz’s condition continued to worsen even as he was seen several times at the center’s medical clinic. In audio recordings obtained by ABC News, Cruz’s cellmate can be heard in phone calls telling his wife that Cruz was not receiving the care he needed, a claim he would later reiterate in his sworn deposition in the wrongful death lawsuit filed by the Cruz family.

In the lawsuit, brought against the U.S. government and CoreCivic, the family claims Cruz “would be alive today if the authorities had honored their legal and moral duty to care” for him. The case is ongoing.

Gerardo Cruz was a farmer from a small village in Michoacan.(ABC News) Gerardo Cruz was a farmer from a small village in Michoacan.

ICE declined to answer specific questions about either case, citing pending litigation, but issued a statement saying “ICE takes very seriously the health, safety and welfare of those in our care.”

CoreCivic, in a statement provided to ABC News, stressed that ICE is “solely responsible” for medical services in detention centers, denied allegations that Cruz was not provided with timely access to appropriate medical care and said the company “cares deeply about every person entrusted to our care….Our immigration facilities are monitored closely by our government partners, and every one of them are required to undergo regular review and audit processes that include ensuring an appropriate standard of living for all detainees.”

Critics say these cases are not isolated. Human Rights Watch, the prominent international research and advocacy organization, obtained medical records for 52 ICE detainees who've died since 2010, and their experts concluded that almost half of those death were linked to substandard healthcare.

And in a scathing report published in January, the Department of Homeland Security’s Office of Inspector General determined that ICE has failed to hold its contractors accountable to performance standards, even in the face of “serious” problems, at 106 detention facilities subject to its review.

“Despite documentation of thousands of deficiencies and instances of serious harm to detainees that occurred at these detention facilities, ICE rarely imposed financial penalties,” the report reads. “ICE also needs to develop or enhance policies and procedures to ensure that those responsible for contract oversight have access to information necessary to do their jobs and receive adequate guidance about the actions available to them when contract performance standards are not met.”

In response to the report, ICE’s chief financial officer Stephen Roncone accepted the IG’s recommendations but wrote that the agency “disagrees with some of the OIG’s conclusions” about its alleged lack of oversight of contractors, pointing to “multiple facilities where ICE terminated the agreement, removed all detainees from the facility, or scaled back its usage of the facility based on non-compliance issues.”

But Vargas isn’t the only lawmaker stepping up scrutiny.

Rep. Pramila Jayapal, D-Wash, speaks at a news conference on Capitol Hill, , Jan. 30, 2019, on a reintroduction of a resolution to end U.S. support for the Saudi-led war in Yemen.(Andrew Harnik/AP) Rep. Pramila Jayapal, D-Wash, speaks at a news conference on Capitol Hill, , Jan. 30, 2019, on a reintroduction of a resolution to end U.S. support for the Saudi-led war in Yemen.

Rep. Pramila Jayapal, a Democrat from Washington, cited the ABC News report as she blasted DHS Secretary Nielsen over the standard of medical care in immigration detention centers at a congressional oversight hearing on Capitol Hill in December.

The ABC News report, she said, raised questions whether “improper medical care in Department of Homeland Security detention facilities may have contributed to the death of Gerardo Cruz,” Jayapal said.

Jayapal asked Nielsen specifically if she was aware of Cruz’s death, one of dozens of detainee deaths that have occurred since 2010, and pushed Nielsen to commit to additional accountability measures.

“Can you assure the members of this committee that not a single additional death will result because of negligence on the part of your agency?” Jayapal asked Nielsen.

“I can assure you that I hold the men and women of DHS accountable and we are always consistently reviewing,” said Nielsen, after acknowledging that she was aware of Cruz’s case. “We have some of the highest standards in the world as you know but our goal is always to take care of those in our custody. ... You have my commitment to ensure that all of our detention centers take good care of those in our care.”

Secretary of Homeland Security Kirstjen Nielsen waits to testify to the House Judiciary Committee hearing on oversight of the Department of Homeland Security on Capitol Hill in Washington, D.C., Dec. 20, 2018.(Joshua Roberts/Reuters) Secretary of Homeland Security Kirstjen Nielsen waits to testify to the House Judiciary Committee hearing on oversight of the Department of Homeland Security on Capitol Hill in Washington, D.C., Dec. 20, 2018.

And on Nov. 15, nearly a dozen Democratic senators sent a letter to CoreCivic president and CEO Damon Hininger – and to the CEO of the GEO Group, another company that runs detention facilities on behalf of ICE – expressing concern about the treatment of detainees in their facilities and requesting information about their respective operations.

One of the letter’s signees, Sen. Richard Blumenthal, a Democrat from Connecticut, told ABC News that he plans to push for a review of the government’s policies, saying the issues raised in the ABC News report are “a call to action.”

“Shining a light on these kinds of failings [of medical care in detention facilities], and they are failings of morality as well as law, ought to be one of our mandates in the earliest days of the next Congress,” Blumenthal said. “We need hearings, oversight, investigation, fact finding, evidence, because this administration must be held accountable.”

ABC News’ Anne Flaherty and Jinsol Jung contributed to this report.