Editor's note: This is the first part of a two-part series on Maria Hinojosa and her expose on undocumented children detained while crossing the border.

Detention center holding rooms meant to hold 40 to 50 captives are packed with twice that amount. The unaccompanied, undocumented migrant children within don't have sheets, pillows, or even beds, and many sleep standing up, balanced against an upright neighbor, because there's no room to lie down. Staff members who work in these centers complain openly about "baby sitting, diaper changing, burrito wrapping, and cleaning cells," rather than addressing the emotional and physical needs of the children who they are tasked to look after; children who've survived dire circumstances and crossed blistering deserts .

Five years ago, 19,000 unaccompanied, undocumented minors entered the United States, seeking improved lives. This year alone the government expects that 90,000 unaccompanied children will enter the U.S., in search of their parents, better lives, and prosperity; instead, they will encounter captivity. Customs and Border Protection, which is supposed to detain children for a maximum of 72 hours, often holds children from 10 days to two weeks before transferring them to the Office for Refugee Resettlement in the Department of Health and Human Services, where they, again, may be detained. Due to inadequate processing, they are housed with dozens of strangers under the guise of it being within their "best interest." International human rights standards state that detention should only be a last resort, and only for a short period of time for unaccompanied children, particularly because research studies have linked immigration detention with mental health consequences.

Maria Hinojosa, host and executive producer of NPR's "Latino USA" and the founder of Futuro Media Group, recently aired an episode of "Latino USA" entitled "Kids!" where she spoke with an anonymous whistleblower, using the name 'K', who shared their experience as an employee at a detention center.

Hinojosa called K a hero during an interview with Latin Post, where the Emmy-winning journalist shared how her roots in activism led her to "delivering the truth" as journalist and telling "untold stories and making the invisible visible." She took a moment to thank K for their bravery.

"[From K], I learned about the children's reality, and about what it means to be a whistleblower. K spoke up, and K didn't have to," Hinojosa said.

Migrant children arrive in the U.S. every day, looking to escape humanitarian crises in their own countries. While their thousand-mile journeys are riddled with threats of rape and death, it's the "horror of being detained in the U.S." that frightens them most, K said. According to K, children as young as 7 years old explained what the trip north was like and about the conditions they suffer in the facility.

"I saw the look of fear on their faces, and that's when I realized that this is a vulnerable set of kids that I'm working with; this is real work," said K, whose voice was cloaked to hide his or her identity. "I think these kids want to tell their stories. I don't think they know that they can, or that they're allowed to. So, I asked them questions about where they're from and how long it took them to get here, and immediately they started to open up about everything else; they continued on for half an hour."

The story of the these children, according to K, is not about traveling to the United States, which takes weeks or months, but more about la hielera or the detention centers where they are held. "La hielera is pretty much like a cooler. We, in our facility, have a kitchen. And one kid was like, 'do you know what the walk-in freezer is like downstairs, or in the walk-in refrigerator?' He said, picture being in there every day, all day, 24-7, for up to a week. That's how cold it is," said K.

Children spoke out about only being fed once or twice a day: bologna sandwiches, which were usually frozen, or breakfast burritos. Often, the children said that they weren't able to shower or brush their teeth, and were forced to share bathrooms with 80 or more people. The children, having escaped lives of violence, are returned to it; the children endure discipline from administrators at the understaffed facilities, who often bark orders at them.

K said children left their hpme countries because they received daily threats from gang members. Some children even witnessed the death of family members. "Five kids, five brothers and sisters, came to our facility because their mom was kidnapped and murdered, all because of money and gang violence. A lot of the participants I talked to expressed not wanting to be in gangs, but gang members went [to their homes] asking for them, and, at that point, if you don't listen to them, then it's a danger on your family."

To hear more of Hinojosa's insights, tune in to "Latino USA" or check her out on Twitter and Facebook.