The move by the Trump administration to add a citizenship question to the census can be traced back directly to the work of a Republican redistricting expert who studied how to create maps that “would be advantageous to Republicans and Non-Hispanic Whites,” according to new evidence revealed in court documents filed Thursday.

How the evidence even fell into the challengers’ laps is in itself an incredible turn of luck, involving an estranged daughter, a chance phone call and a casual conversation about how the files of the GOP’s gerrymandering mastermind might be useful to voting rights lawyers.

The documents — filed by the challengers in the case in New York seeking to block the question — offer the most concrete evidence yet that the Trump administration added the question in order to boost the GOP, rather than to better enforce the Voting Rights Act — its official rationale.

The challengers already won their case at the trial court level, but it has been appealed and was heard by the Supreme Court last month. A final decision on whether the question will stay on the 2020 census is expected in June.

The new evidence backs the case made by the challengers that the administration lied about its reasons for adding the question, and, over the course of the litigation, further concealed the citizenship question’s true origins. It supports other evidence that adding the question was part of a long-held goal by conservative advocates to overhaul redistricting in a way that shifts political power away from urban and diverse communities.

According to the new evidence, Thomas Hofeller — the Republican Party’s go-to redistricting expert who died last year — was behind language that made it into the Justice Department’s formal request in December 2017 that the question be added to the census.

The evidence was found in a hard drive provided by Hofeller’s estranged daughter, who first shared it with the challengers in a partisan gerrymandering case in North Carolina. She had reached out to the challengers, the voting rights group Common Cause, to find a lawyer to help her settle her father’s estate, the New York Times reported. She mentioned to a member of the group, only in passing and after several conversations, the hard drives of Hofeller’s personal laptop that she had found while going through his personal belongings. The staffer then brought up that Common Cause had brought the lawsuit in North Carolina, and the daughter thought “Wow — this might be of use,” as she told the Times

Coincidentally, a D.C.-based law firm that was assisting the North Carolina challengers was also involved in the census case in New York. The treasure trove of Hofeller’s digital files was shared among those challengers as well, leading to the discovery of the smoking gun now being put forward in the census case.

What they found is that Hofeller conducted an analysis in 2015 on how excluding noncitizens in redistricting “would clearly be a disadvantage for the Democrats,” using the Texas legislature as a case study.

“A switch to the use of citizen voting age population as the redistricting population base for redistricting would be advantageous to Republicans and Non-Hispanic Whites,” the study said.

The study was commissioned by GOP mega-donor Paul Singer, a major funder of the Washington Free Beacon, who was considering whether to financially support a lawsuit that sought to require that noncitizens be excluded from redistricting.

Hofeller’s study cautioned that such a redistricting overhaul would be “functionally unworkable” without a citizenship question on the Census.

Hofeller went on to advise the Trump transition on the census, and was the “first person” to suggest that a citizenship question be added, according to the deposition of another transition advisor, Mark Neuman.

Neuman claimed in his deposition that Hofeller recommended the question to “maximize” Latino population – testimony that the challengers in the New York case say is false and worthy of court sanction.

After the trial in the case was finished and the district court judge had handed down his decision, it was revealed that John Gore, the DOJ official behind the December 2017 question request, had received a draft of the request provided to him by Neuman. The revelation came in a congressional interview of Gore, and the New York challengers are also seeking that Gore be sanctioned for false testimony in the legal case.

Neuman’s draft was in fact ghostwritten by Hofeller, according to Thursday’s court filings, which point to a file on his hard drive with the meta data showing it was created in August 2017. Language verbatim from the Hofeller file made it to Neuman’s draft, which in turn bears many striking similarities to Gore’s formal request. There are even key points in the final request that can be traced back all the way to Hofeller’s 2015 study.

The new documents fill in the picture of what voting rights advocates long suspected was the true motive for adding the citizenship question.

Commerce Secretary Wilbur Ross, who oversees the census and made the call to add the question, was able to avoid a deposition in the New York case. But emails produced in the litigation show that he was pushing for the question to be added from the early days of the Trump administration. The efforts by his aides to do so — by securing a request from another agency — were first rebuffed by the Justice Department and by the Department of Homeland Security in the summer of 2017.

Ross only increased the pressure on his aides, and even sought the intervention of then-Attorney General Jeff Sessions to see to it that the Justice Department submit the formal request, which claimed data from the question would enhance its enforcement of the Voting Rights Act. Around the time Ross aides were scrambling to figure out how to add it, Hofeller was helping to write the VRA rationale, according to the documents filed Thursday.

The rationale was from the beginning viewed with extreme skepticism by civil rights advocates, who note that the question will in fact discourage the participation of immigrant communities on the census, resulting in an undercount that will skew political representation and government resources away from them.

Thursday’s revelation only reenforces their suspicions that the question was specifically added specifically to diminish the political representation of immigrant and urban communities. It now turns out that the VRA rationale was in fact partially written by a redistricting expert who had studied how excluding noncitizens from redistricting would boost the electoral advantages of non-hispanic whites and Republicans.

Read the court filings below: