Top Trump adviser and lawyer Boris Epshteyn is scheduled to meet Thursday with special counsel Jack Smith's prosecutors as part of the probe into former President Donald Trump's attempt to overturn the 2020 election, sources familiar with the matter told ABC News.

The interview, requested by the special counsel's office, comes as multiple other top Trump advisers have appeared before a grand jury investigating Trump's actions leading up to the Jan. 6 attack on the U.S. Capitol.

It's not immediately clear why investigators are not seeking Epshteyn's testimony before the grand jury probing the matter, or whether that's a step they will ultimately take.

Epshteyn could not be reached for comment by ABC News.

A spokesperson for the special counsel declined to comment.