Documents discovered in hard drives of a deceased Republican redistricting strategist show he was in direct contact with a top census official as early as 2015 about adding a citizenship question to the decennial survey, and lawyers say the strategist’s business partner evaded a subpoena for computers he took from the strategist’s house upon his death.

The information provides further evidence connecting the strategist, Thomas Hofeller, to the Trump administration’s quest to add a citizenship question to the 2020 census, say civil rights groups challenging the question.

Attorneys for the Mexican American Legal Defense and Educational Fund (MALDEF), Asian Americans Advancing Justice (AAJC), and individual plaintiffs, filed material Friday to Maryland U.S. District Court Judge George J. Hazel indicating that Thomas Hofeller, who died in August, was in direct contact in 2015 with Christa Jones, now chief of staff to the deputy director of the U.S. Census Bureau, over adding the question.

“These newly discovered documents … eliminate any colorable doubt about the link between Hofeller and government employees involved in the citizenship question approval process,” the plaintiffs’ lawyers wrote in a letter to Hazel.

The documents show that Jones, then a special assistant at the bureau, communicated directly from her private email address with Hofeller about the citizenship question, alerting him to a Federal Register notice for comment on the bureau’s 2015 content test, which she suggested “could be an opportunity to mention citizenship as well."

“Ms. Jones’s direct private contact with Hofeller about the citizenship question refutes Defendants’ contention that no link between Hofeller and the Secretary can be shown,” the letter said.

In a statement, the Commerce Department said “neither Dr. Hofeller nor his views were part of [Secretary Ross’s] decision to reinstate the citizenship question on the 2020 Census," and called the narratives of the plaintiffs “conspiracy theories.” The Justice Department declined to comment.

Documents released last year in legal challenges to the question also showed Jones participated in internal bureau discussions about the question and, in correspondence with the bureau’s then-acting director in February 2018, suggested people who might be called upon to publicly support the question.

The filing comes two weeks after material came to light linking Hofeller to the administration’s discussions over the question and suggesting he was the one who came up with the government’s stated rationale for adding it: to help enforce the 1965 Voting Rights Act.

Hofeller had also done a study in 2015 that concluded a citizenship question on the census would result in a structural electoral advantage for Republicans and non-Hispanic whites.

Earlier this year, Hazel was one of three federal judges who ruled against the question, saying it violated the Administrative Procedure Act. But he did not find evidence to support charges of conspiracy and intent to discriminate.

The government appealed to the Supreme Court, which is expected to rule by the end of this month; during oral argument in April, the high court’s conservative justices seemed inclined to let the government add the question.

But after the Hofeller files came to light late last month, civil rights groups asked U.S. District Judge Jesse Furman in New York to consider sanctions against the government, and asked the Supreme Court to delay its ruling.

In Maryland last week, plaintiffs’ lawyers asked Hazel to reconsider whether the government intended to discriminate against immigrants, Latinos and Asian Americans by adding the question, or whether adding the question was part of a conspiracy within the Trump administration to violate the constitutional rights of noncitizens and people of color. A hearing on the issue is scheduled Tuesday in Greenbelt.

But earlier this month it called the Hofeller-related claims “frivolous,” saying there was no evidence that administration officials were aware of the strategist’s study and accusing plaintiffs of trying to derail the Supreme Court decision.

Opponents of the question have argued it will suppress response to the survey among immigrant communities, resulting in an undercount in the areas where they live.

Evidence of Hoffler’s involvement was found accidentally by his estranged daughter after this death on hard drives belonging to him. Stephanie Hofeller Lizon then shared them with the organization Common Cause for a gerrymandering lawsuit it is pursuing in North Carolina.

Hofeller Lizon testified at a deposition that her father’s business partner, Dalton Oldham, went to her parents’ home around the time of her father’s death and took two computers. Oldham and Hofeller were longtime business partners in political and redistricting work; the two had a political consultancy together called Geographic Strategies LLC.

Lawyers for plaintiffs in the North Carolina gerrymandering case, Common Cause v. Lewis, said they tried to subpoena both Oldham and the LLC, but Oldham evaded service of the subpoenas, even when a local sheriff in South Carolina attempted to serve him.

It is unknown what files were contained on the computers Oldham is said to have taken, but attorneys for plaintiffs in the North Carolina case believe they contain documents from 2017 and 2018 that are more recent than the material on the hard drives.

Oldham did not return a request for comment.

As Common Cause continues to sift through material from the hard drives, it alerted plaintiffs’ lawyers Thursday to evidence of Jones’ involvement.

Kathay Feng, national redistricting director for Common Cause, said the Jones-Hofeller emails cast further doubt on the government’s claims.

“Why would she use her personal email? Why would she email a partisan operative about a topic that was not under consideration at the Census Bureau?” Feng said. “The new documents eliminate any doubt about the link between the Republican gerrymandering mastermind and the citizenship question.”