WASHINGTON (CN) — Calling for grand jury records in the special counsel’s investigation to be made public, a lawyer for House Democrats told the D.C. Circuit on Monday about mounting evidence that the president lied to Robert Mueller.

House attorney Douglas Letter made the case this morning just days after Roger Stone, the longtime adviser to President Donald Trump, was found guilty of seven felony counts.

Letter said evidence from Stone’s case and that of Trump’s convicted former campaign manager Paul Manafort “shows very clearly” that Trump may have lied to Mueller.

“They are lying about things that go directly to the Mueller report,” Letter said.

A federal jury found Stone guilty of falsely testifying that he did not communicate with the Trump campaign about WikiLeaks releasing Russian-hacked documents. Witness testimony from a top campaign aide indicated that Stone spoke directly with Trump about WikiLeaks dumps in July 2016.

Trump never sat with Mueller for an interview, but the written responses he provided denied any such communications with Stone.

As Letter told the D.C. Circuit, a big question emerges: “Was the president not truthful in his responses to the Mueller investigation?”

The argument appeared to hold sway with U.S. Circuit Judges Thomas Griffith and Judith Rogers, but the Trump-appointed U.S. Circuit Judge Neomi Roa seemed skeptical. Roa focused her questions on the court’s jurisdiction, questioning whether the panel would be overstepping Supreme Court precedent by “impermissibly” involving itself in the impeachment inquiry.

Roa noted as well the “irreparable harm” that could flow from the release of grand jury material.

But Judge Rogers repeatedly questioned what bar the Justice Department set for the release of grand jury material and how the House could provide a more specific request.

“If it’s secret, and they don’t know, how can they say more than they did?” Rogers asked.

A George W. Bush appointee, Griffith later remarked that the House Judiciary request seemed in line with the purpose of special counsel investigators to “engage in fact-finding and they pass it along to the House of Representatives.”

Roa asked Letter meanwhile whether the House was suggesting there was “no presumption of grand jury secrecy.”

Letter responded that it was common for grand jury material to be presented as evidence in court proceedings — as happened with the prosecution of Stone.

As noted by Judge Griffith, the dispute takes on special significance given the impeachment inquiry now dominating Washington.

“This isn’t a normal proceeding,” he said. “It isn’t.”

Justice Department attorney Mark Freeman faced a volley of questions meanwhile from Judge Rogers, a Clinton appointee who made no secret of her opinion that found the House has demonstrated sufficient need for the materials.

When Freeman broadly stated the House sought to do away with the veil of secrecy on all grand jury material from the investigation, Rogers shot back: “No they didn’t … they were quite clear as to what they were seeking.”

Freeman’s argument relied heavily on maintaining grand jury secrecy, but provided little response to questions from both Griffith and Rogers on any potential risk now that the Mueller investigation has ended.

The Justice Department attorney proffered that there is material linked to ongoing criminal investigations that must remain protected.

But Letter called it a “bogus point.” Attorney General Bill Barr has permitted Letter — along with the House Judiciary Committee, House Intelligence Committee and House Speaker Nancy Pelosi — to view the unredacted Mueller report.

“My memory is there is only one instance of a claim to … harm to ongoing investigation,” the House attorney said.

Responding to concerns from the court on the safety of the material in the hands of lawmakers, Letter said U.S. District Court Judge Beryl Howell “ordered a very carefully staged disclosure” when she granted the request.

He also pointed out that the Watergate grand jury roadmap, turned over to the House during its investigation of President Richard Nixon, remains undisclosed to the public.

But Freeman continued to condemn language in the House court documents that the request was critical to “investigate fully,” saying a congressional impeachment inquiry is not a judicial proceeding and thus cannot merit the release of grand jury material.

“This is not go look at anything you want, that’s what I’m trying to get at,” Judge Rogers said in response. “It’s not a fishing expedition.”

The court took the Justice Department motion to stay under advisement and will issue a decision in the weeks ahead.

Meantime in the impeachment inquiry, public testimony resumes Tuesday on reports that Trump illegally pressured Ukraine to open an investigation into his political rival, former Vice President Joe Biden.