Former President Donald Trump's one-time director of national intelligence, John Ratcliffe, appeared before a federal grand jury investigating Trump's attempt to overturn the 2020 election, sources familiar with the matter told ABC News.

Ratcliff is the latest former top Trump adviser to appear before a grand jury in Washington, D.C., following a judge's ruling last month that a number of top aides must appear.

Former top aide Stephen Miller was at the court earlier this week, and former Department of Homeland Security official Ken Cuccinelli was spotted there last week. Sources confirm they were appearing before the grand jury.

Both men have previously appeared before the grand jury, but Trump had challenged their grand jury subpoenas by attempting to assert executive privilege.

A judge last month ordered former chief of staff Mark Meadows and other former top Trump aides to testify or provide additional grand jury testimony to the grand jury probing attempts to overturn the election, ABC News was first to report.

Also included in the judge's order were aides Dan Scavino, Robert O'Brien, Nick Luna and John McEntee. It was not immediately clear whether dates had been set for them to appear.