Federal prosecutors investigating former President Donald J. Trump’s attempts to overturn the 2020 election have questioned multiple witnesses in recent weeks — including Mr. Trump’s son-in-law, Jared Kushner — about whether Mr. Trump had privately acknowledged in the days after the 2020 election that he had lost, according to four people briefed on the matter.

The line of questioning suggests prosecutors are trying to establish whether Mr. Trump was acting with corrupt intent as he sought to remain in power — essentially that his efforts were knowingly based on a lie — evidence that could substantially bolster any case they might decide to bring against him.

Mr. Kushner testified before a grand jury at the federal courthouse in Washington last month, where he is said to have maintained that it was his impression that Mr. Trump truly believed the election was stolen, according to a person briefed on the matter.

[So … I guess that strategy won’t work, then. If Trump was going to admit that to anyone, it would be inner circle, and Kushner is as inner circle as it gets. — Ed]