How to Reverse-Engineer an ICE Investigation?

A number of people have emailed since my ICE story was published in The New York Times Magazine to ask how I was able to learn who the deportation officers were searching for in Washington State databases, and when they searched, and how I got a record of the searches. The short answer is that I filed dozens of public-records requests over the course of a year, and instead of sending them to ICE, I sent them to state and local agencies.

The longer answer:

•Thanks to other reporters, I knew both that ICE was making use of local-government data and that Washington's Department of Licensing had been emailing information to ICE. Was the DOL giving ICE database access in addition to responding to deportation officers' emails? I had a hunch.

•This hunch was worth pursuing in part because many of the databases ICE uses, according to procurement records and DHS records, are in-house federal systems or subscription-based commercial systems like CLEAR, from Thomson Reuters. Though DHS publishes Congressionally mandated privacy-impact assessments of its federal systems, and though Thomson publishes promotional materials, my odds of getting a glimpse of these systems' inner workings—let alone a glimpse of what searches ICE officers ran through them—seemed minuscule. State and local agencies like the DOL, on the other hand, can be laudably responsive to public-records requests.

•As I quickly learned, the DOL has a database called DAPS—Driver and Plate Search—and on the department's own website I found a document entitled Department of Licensing Agreements with Public Entities. Among the hundreds of public entities (17 pages' worth) that had signed contracts with the DOL were five field offices and sub-offices of ICE. The document suggested that these offices indeed had access to DAPS.

•I was aware that many modern databases have an audit log. Much as Google retains information about your searches so it can better target advertising, DMV and law-enforcement systems retain information about users' searches in order to provide tech support and to ensure that the systems aren't being abused.

•Washington State has very broad public-disclosure laws. Other states vary. Here's a good state-by-state guide: https://www.rcfp.org/open-government-guide/

•After I made various public-records requests related to DAPS—for the five ICE contracts, for the DAPS user manual, etc.—and received those documents from the DOL's harried but always professional staff, I realized that I could also put in a public-records request for the DAPS audit log. That is, I could request every search run by individual ICE officers (because I knew their names) or any searches run for a certain license plate (because I knew some of the arrestees' plate numbers) or all the searches run by the ICE ERO office responsible for Pacific County and other parts of Western Washington. (I knew that you could parse out searches by individual ICE office because ICE had five contracts for DAPS, not just one.)

•So, after some bumbling and rewording, I got various pieces of the DAPS audit log from the DOL, including every search entered by ICE deportation officers covering Western Washington State over the course of two years. One ICE field office covering roughly one half of Washington ran more than 100,000 searches through this one computer system in one two-year period. Here's the document I received showing all these searches:
https://keybase.pub/mckenziefunk/DOL/Public%20Disclosure%20ExpandedEDITED%20.xlsx

•Also helpful in filling out the timeline were records of the DOL's emails back and forth with ICE (example), dispatch records from the local Pacific County Sheriff's Office (some of them first obtained by local ACLU volunteers), interviews with arrestees and their families, documents provided to families and lawyers in immigration court, and statements from ICE's media representatives.