The day after the Colorado Times Recorder revealed that ICE has been detaining immigrants in at least nine makeshift facilities throughout Colorado, 31 state lawmakers — led by congressional candidate Manny Rutinel — sent a letter to the leaders of the Department of Homeland Security and ICE stating that the “existence of undisclosed detention sites, ‘hidden in plain sight’ between strip malls and office parks, is unacceptable.”

The lawmakers demanded “immediate transparency and reasonable notice of operations from all private entities or contractors that provide facilities, staffing, transportation, and services” for immigration enforcement operations.”

In an investigation released on Wednesday, Colorado Times Recorder columnist Logan M. Davis documented the presence of at least nine ICE “hold rooms” where ICE held 3,182 people between January and October of last year.

ICE detained people, including children and the elderly, in Colorado’s hold rooms for weeks, without beds, in violation of ICE regulations.

“Colorado’s vulnerable populations are bearing the cost for ICE’s failure to abide by standards,” states the letter.

Previously, ICE publicly acknowledged the presence of only one detention facility in Colorado, located in Aurora and operated by the GEO Group.

Specifically, the lawmakers’ letter calls on immigration enforcement officials to:

“List every Colorado site or location, with any ICE detention-related service, including “hold rooms,” processing sites, transportation hubs, and short-term confinement areas.

“Describe the nature of services provided at each site, including but not limited to; facility lease/space, guards, intake/processing support, transport, medical care, food service, janitorial, language translation, and technology.

“Identify the contracting vehicle(s) authorizing enforcement work (prime contract, task order, intergovernmental service agreement support, subcontract, property lease).

“Provide entities’ written policies and training materials governing screening and protections for children, families, elders, people with disabilities, and medically vulnerable individuals, such as access to medical care, medication continuity, and emergency response. Additionally, we request time-limit custody tracking and controls to prevent prolonged confinement beyond accepted policy limits.

“Provide reports on filed incidents, use-of-force, grievances, medical emergency logs, substantial bodily injury, and deaths/near-deaths associated with Colorado enforcement sites.”

Rutinel at a news conference in front of an ICE hold room in Frederick.

In addition to Rutinel, the letter to immigration officials was signed by Reps. Elizabeth Velasco, Lorena Garcia, Meg Froelich, Jenny Willford, Chad Clifford, Mandy Lindsay, Eliza Hamrick, Kenny Van Nguyen, Andy Boesenecker, Tisha Mauro, Amy Paschal, Javier Mabrey, Yara Zokaie, Steven Woodrow, Bob Marshall, Kyle Brown, Emily Sirota, Sean Camacho, Brianna Titone, Sheila Leider, Jennifer Bacon, and Lindsay Gilchrist.

State Sens. Mike Weissman, Judy Amabile, Adrienne Benavidez, Lisa Cutter, Julie Gonzales, Nick Hinrichsen, Iman Jodeh, Chris Kolker, and Katie Wallace are also signatories to the letter.

ICE didn’t return an email seeking comment from the Colorado Times Recorder.

But it told Denver’s KDVR TV, which reported on Rutinel’s visit to one of the hold rooms in the town of Frederick on Thursday, that it would respond when it was able to. ICE officials did not come to the door of the detention facility when Rutinel knocked yesterday.

Frederick is in Colorado’s 8th Congressional District (CD8), which is the district that Rutinel wants to represent. But he must first win the Democratic primary against former state Rep. Shannon Bird of Westminster and others, and then he needs to triumph over his likely Republican opponent, U.S. Rep Gabe Evans, in November’s general election. The district, located northeast of Dener, is one of the key battlegrounds that will likely determine which party controls the U.S. House next year.

ICE has contracted with the GEO Group to operate a second Colorado detention center in the town of Hudson, which is also in CD8, but there is no information about when or if it will open. Five additional facilities, including one in Walsenberg, have been pitched to ICE for consideration as detention centers as well. None of those potential sites was among the hold rooms revealed in the Colorado Times Recorder’s investigation.

READ MORE: EXCLUSIVE: Secret ICE Detention Facilities Exist Around Colorado, Data Shows

CORRECTION 3/6: This article initially reported an incorrect number of signatories on the letter to immigration officials.