(CNN) Dr. Scott Allen and Dr. Pamela McPherson were used to working behind the scenes, quietly documenting the devastating things they'd seen.

Children's fingers crushed by cell doors. A boy who'd lost nearly a third of his body weight in a matter of days. Incorrect vaccine doses and missed diagnoses.

Each incident, the doctors say, was meticulously noted in reports they filed with the US Department of Homeland Security. Allen and McPherson -- an internist and a psychiatrist -- are expert consultants contracted by the department's Office of Civil Rights and Civil Liberties.

Their mission: inspecting the facilities where US Immigration and Customs Enforcement detains immigrant families.

For years, the doctors' expert opinions, like the facilities they inspected, remained out of the spotlight -- unseen by most lawmakers and unheard by members of the public.

That changed, they say, when the Trump administration's policies left them no choice. The doctors became whistleblowers, speaking out with a dire warning. Family detention isn't safe, they said, and children's lives are at stake.

"We are writing to you, members of Congress with oversight responsibility, because we have a duty to raise our concerns about the ongoing and future threat of harm to children posed by the current and proposed expansion of the family detention program," the doctors said in a letter to the leaders of the Senate Whistleblower Protection Caucus

Their new mission: Showing the world why immigrant family detention should be stopped.

"Detention of innocent children should never occur in a civilized society, especially if there are less restrictive options, because the risk of harm to children simply cannot be justified," they wrote.

That letter was sent nearly a year ago. And writing it changed their lives.

But family detention wasn't scaled back after they spoke out.

On numerous occasions since that day they sent the letter in July 2018, the administration has laid the groundwork for policies that would increase the number of detained immigrant families. In a recent budget request, the White House asked for funding for 960 additional family detention beds -- an increase that would nearly double the number of people housed in one family detention facility in south Texas.

And for Allen and McPherson, what started with one letter to Congress has become a quest with no end in sight.

"Each passing day of continued detention of children -- and no acknowledgment of the risk that we have reported -- alarms me even more," Allen told CNN in a recent interview.

What they witnessed

When the pair began conducting inspections of ICE family detention centers in 2014, they were far from new to the justice system. Allen, who runs a clinic for adults with developmental disabilities in California, is a former medical director for the Rhode Island Department of Corrections. McPherson, a child and adolescent psychiatrist as well as a forensic psychiatrist in Shreveport, Louisiana, has worked in juvenile detention facilities for three decades.

Still, they were surprised and troubled by what they found in the 10 inspections they conducted together at ICE family detention facilities in several states.

After years of inspecting ICE facilities, Dr. Pamela McPherson and Dr. Scott Allen became whistleblowers, speaking out against the conditions children face in immigrant family detention.

Allen and McPherson say they documented their concerns numerous times in reports filed with the Department of Homeland Security during the Obama administration, and felt like the people in power were listening. But they say two things prompted them to speak more publicly about the matter after Trump took office: the spike in family separations at the border and moves to increase family detention rather than scale it back.

"There were rumblings that family detention was going to be increased greatly," McPherson says. "Just the idea that things that we had seen would be magnified and multiplied called us to action."

In their letter to Congress last year, the doctors detailed particularly troubling cases that they said represent systemic problems that would only get worse if family detention expands:

• Significant weight loss in children that went largely unnoticed by the facility medical staff, including a 16-month-old baby who lost nearly a third of his body weight over 10 days during a diarrheal disease but was never given IV fluids or sent to an emergency room.

• A 27-day-old baby who had a seizure from bleeding inside his skull that was missed by the facility on arrival.

• Numerous children who suffered severe finger injuries while confined in a facility that was designed as a medium-security prison for adults.

"That one really bothered me," Allen says, describing how they uncovered the pattern by combing through the charts of children who'd been taken to the emergency room.

"These are shattered fingers, significant lacerations -- probably some of the injuries disfiguring. And you start to think about how they're happening. And they're these heavy, spring-loaded doors in a facility that was constructed to have adult males ... and the light bulb goes on that this is a complete disaster," he says. "Because they're using cells, but they paint them pretty colors and they now call them dorm rooms. But it's got the same door."

Once the problem was pointed out, he says, officials were still slow to correct it -- something that Allen says was "very discouraging to see."

"Somewhere out there there's kids walking around with disfigured fingers for the rest of their life," he says, "because no one could really get their act together to fix that problem."

It's just one example, the doctors say, of how family detention endangers children. They stress that doesn't mean staff inside the facilities aren't trying to do the right thing.

"This is not a story about people in these facilities not caring about children. ... It is about good people trying to keep children safe in an environment that's very dangerous to them by design, if not intent. And they've been asked to execute deeply flawed and I would even say mean-spirited policies, and to do so in such a way that minimizes harms to children," Allen says. "It's an impossible task."

And no amount of effort can truly fix the problems, he says, describing any attempts to improve conditions in family detention as "Band-Aid solutions" that are doomed to fail.

"Even if you could pour money and resources into properly staffing these facilities and giving them programming," Allen says, "the simple act of detaining and indefinite detention ... is irreparably harmful to children."

ICE defends its facilities

But ICE has repeatedly defended the facilities in the face of criticism. Facing a harsh grilling from lawmakers last year, one top ICE official countered that family detention facilities are more like summer camps than jails

"There's basketball courts, there's exercise classes, there's soccer fields that we put in there," he said. "They have extensive medical, dental and mental health opportunities. In fact, many of these individuals, the first time they've ever seen a dentist, is when they've come to one of our (family residential) centers."

That official, Matthew Albence, has since been promoted to be the acting director of the agency.

In this August 2018 photo provided by US Immigration and Customs Enforcement, immigrants enter a building at the South Texas Family Residential Center in Dilley, Texas.

Asked for a response to the concerns Allen and McPherson have documented in their letters, an ICE spokeswoman cited a June 2017 report from the DHS inspector general , describing the facilities as "clean, well-organized and efficiently run."

"Family residential centers provide a safe location for family units encountered by the Border Patrol as they are processed for release into the United States with notices to appear in immigration court," ICE spokeswoman Danielle Bennett said in a written statement. "U.S. Immigration and Customs Enforcement (ICE) ensures that these residential centers operate in an open environment, which includes medical care, play rooms, social workers, educational services, and access to legal counsel."

A Department of Homeland Security spokesman also defended the facilities when asked about the doctors' concerns.

"DHS takes our responsibility to care for those in our custody extremely seriously," he said. "We do everything in our power to ensure the safety of every child in our detention facilities."

Deciding to speak out

When Allen and McPherson decided to speak out, they reached out to the Government Accountability Project, known for its work protecting whistleblowers, and asked for help.

They also spoke with their families and warned them there'd be a long road ahead. McPherson told her neighbors that TV cameras might show up on their street.

Then they braced themselves.

Dana Gold, senior counsel for the Government Accountability Project, represents Allen and McPherson and says whistleblowers like them often face serious repercussions.

"It could be disparagement. It could be tremendous amounts of hostility. They could be blacklisted in their field," she says.

So far, the doctors say they haven't faced professional pushback. In fact, they've been honored for taking a stand by groups like Physicians for Human Rights and the Ridenhour Truth-Telling Prizes.

But they're still aware that each time they share their story, they're taking the risk all over again.

"To some extent I'm still nervous. I think we live in a time where sort of normal decency and normal rules don't seem to apply, and people can be quite vicious," Allen says. "So I'm not cavalier about our situation. ... We try to proceed at each step cautiously while at the same time doing what we have to do."

And while they've been lauded by colleagues and friends, there are two things McPherson and Allen say haven't happened since they wrote their first letter to Congress.

The doctors haven't been asked to inspect any family detention facilities again.

And the government's family detention policies haven't changed.

Plans to increase detention

Three ICE facilities in the United States regularly house detained immigrant families: the South Texas Family Residential Center in Dilley, Texas; the Karnes County Residential Center in Karnes City, Texas; and the Berks Family Residential Center in Leesport, Pennsylvania.

As of last week, more than 1,200 family members were in immigrant detention, according to ICE -- 1,223 at Dilley and 13 at Berks. Karnes is temporarily housing only single adult women, ICE says. Officials have said the facility will return to housing families again later this year.

The Trump administration has taken several notable steps in the past year to pave the way for increased family detention:

• In his executive order announcing an end to family separations, President Trump wrote that the administration would keep families together "including by detaining alien families together where appropriate."

• Officials have proposed new regulations that would circumvent a federal court settlement that limits the amount of time children can be detained to 20 days. If implemented, the administration's plan would allow for indefinite family detention.

• In budget requests, officials have repeatedly outlined plans to increase family detention capacity. The White House's proposed 2020 budget includes a plan to expand capacity to 10,000 family detention beds, a request that would quadruple the number of beds currently funded. And a recent emergency budget request to Congress asked for funding to add 960 beds to the Dilley facility.

Detainees watch TV on August 9, 2018, at the South Texas Family Residential Center in Dilley, Texas. This photo was provided by U.S. Immigration and Customs Enforcement.

• Officials say the administration is weighing the possibility of targeting more families for deportation to deter other migrants from making the trek north to the US border. While they haven't said whether those plans would involve detaining families, given the logistics involved in planning deportation flights, it's likely any large-scale effort to deport more people would also involve immigrant detention.

Allen and McPherson say they're concerned about all this and troubled by another fact: The last time they were asked to inspect an ICE family detention facility was in September 2017.

"Such a lapse in oversight is alarming," the doctors wrote in another letter to Congress in March , calling for lawmakers to pass a law banning any detention of children due to what they said was "DHS's proven inability to provide necessary medical and mental health care to the immigrant population crossing the southern border."

Allen and McPherson are still contracted subject-matter experts performing work for the DHS Office of Civil Rights and Civil Liberties, including medical record inspections and onsite investigations, a DHS official told CNN.

The office has received 36 allegations related to ICE's family detention facilities since then, the official said, but hasn't conducted any inspections of the facilities because staff have been working with ICE to implement recommendations submitted after the 2017 inspection.

"We have plans to conduct a follow-up investigation in (fiscal year 2020), in order to both assess implementation of our 2017 recommendations and investigate any recent complaints we may receive," the official said.

'We've put everyone on notice'

To Allen and McPherson, the expansion of family detention is the worst possible outcome.

"The practice of detaining children and families is no longer an issue of policy dispute," they wrote in their March letter to Congress. "It is a willful policy that knowingly inflicts serious harm to children, including risk of death."

The doctors say the problems detailed in their letters illustrate how difficult it is to provide care to vulnerable children in relatively small detention facilities.

"Now you take that, and you try to rapidly upscale it. This is going to be a disaster," Allen says.

But he says it doesn't have to be.

Because of policy decisions, Allen says, children and families are placed in confinement first, with appropriate triage and medical care occurring later.

"That's exactly the wrong way to do it," he says. "As doctors, we say, triage them, make sure they're safe, make sure they're healthy, and then put them through the process of asylum."

That approach, Allen and McPherson argue, should be followed in community settings, not behind bars.

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"When you go through that metal detector and those series of locked doors, and then you see children playing and women walking around carrying young children, it's just sort of a surreal experience," McPherson says. "I don't think you can experience that without questioning, 'Why are these children in a secure facility? Why are these children in what used to be an adult prison?' It's jarring."

As long as policies aimed at increasing family detention continue, the doctors have vowed to continue to speak out about its dangers.

"We are not going away, and we are leaving a written and clear record that we've put everyone on notice that we possibly can," Allen says. "Our goal is to protect children. But if we fail them, we sure as hell want to leave a written record for history that documents who is notified of an impending harm to children -- and who did nothing about it."