Senate Judiciary Committee ranking member Dianne Feinstein, D-Calif., sent more letters Tuesday as part of the committee’s ongoing Russia investigation.

The four letters come less than three weeks after she sent other letters to former Trump campaign aides to provide information amid the Judiciary Committee’s probe into Russian meddling in the 2016 presidential election and possible collusion with the Trump campaign.

Like the letters sent in November, committee Chairman Chuck Grassley, R-Iowa, did not sign them.

In a letter to K.T. McFarland — who served on President Trump’s transition team before becoming the White House deputy national security adviser — Feinstein says she believes she has key information, and the congresswoman would like to interview her in January 2018. McFarland is currently Trump's nominee to be the U.S. ambassador to Singapore.

It has been reported that McFarland was the “senior official” on the Trump transition team that former national security adviser Michael Flynn called to discuss his communications with then-Russian ambassador Sergei Kislyak.

Feinstein notes this and that McFarland reportedly emailed other Trump officials about U.S. sanctions against Russia on how they would make it harder for Trump to ease tensions with the nation.

McFarland also attended the Republican National Convention with other members of Trump’s campaign, which was also attended by Kislyak.

Because of these connections, Feinstein wants records from June 15, 2015 to present, including all documents about the the “selection, termination or resignation” of Flynn; all documents concerning Flynn’s conversations or meetings with Kislyak or other Russians; all documents to, from, copying, or referencing Flynn related to foreign policy on Russia, Turkey, Turkish Islamic preacher Fetullah Gulen, Kislyak, former FBI Director James Comey, or other foreign government officials or people who appear to be acting on behalf of a foreign government; and all communications concerning Russian interference and emails of the Democratic National Committee, John Podesta,or Hillary Clinton.

Feinstein requests McFarland turn over the documents by Dec. 30.

Feinstein also sent similar requests to Monica Crowley — a political commentator who was a deputy national security adviser for Trump’s National Security Council for roughly a month — and former communications adviser for Trump’s campaign and transition team Chris Byrne.

In those letters, Feinstein asks for an interview and documents related to Flynn’s communications with Kislyak and U.S. sanctions against Russia, as well as contacts between the campaign or transition team and Russian officials. Crowley and Byrne are also asked to turn over documents regarding the Republican Party’s platform regarding Ukraine.

Kory Langhofer, a well-known lawyer who represented Trump for America and the Nevada Republican Party during the 2016 campaign, was also sent a letter. Feinstein asked Langhofer to turn over documents from the Trump transition team as a whole, including on Flynn’s communications with Kislyak.