Constitutional law professor Jonathan Turley said special counsel Jack Smith will need "direct and strong evidence" in order to bring an indictment against former President Trump in the grand jury's January 6 investigation. On "America's Newsroom" Tuesday, Turley said Trump's target letter from the DOJ is a likely indication of a coming indictment, but argued the then-president's Ellipse remarks are "entirely protected" political speech.

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JONATHAN TURLEY: They have to really stick the landing so that no one will question it or few people would question it. That's going to require some very direct and strong evidence. We haven't seen that. So if Smith doesn't have that type of evidence, and he's moving forward largely on the speech, then I think he will fulfill the narrative of Donald Trump. He will be the federal version of Alvin Bragg in bringing that indictment. … Smith has a reputation of stretching the criminal code sometimes too far. This is not an occasion for that. If you're going to indict the former president over January 6, you're going to need a lot of evidence showing that he was doing more than engaging in a political speech. In my view, what Donald Trump said in the Ellipse is entirely protected under a case called Brandenburg and the First Amendment. Smith is going to need a lot more than that speech.

Trump said Tuesday he received a letter from Smith stating that he is the target of a Jan. 6 grand jury investigation.

The former president posted on Truth Social that he initially received the letter on Sunday and said he expects to face both an arrest and indictment. 

A government source with direct knowledge of the situation also told Fox News that Smith’s office sent Trump a target letter. 

"Deranged Jack Smith, prosecutor with Joe Biden's DOJ, sent a letter (again it was a Sunday night!) stating that I am the TARGET of the January 6th Grand Jury Investigation, and giving me a very short four days to report to the Grand Jury, which almost always means an arrest an indictment," Trump wrote.

Fox News' Brooke Singman and Anders Hagstrom contributed to this report.