STORY: WARNING GRAPHIC CONTENT

Jury selection in Donald Trump's historic New York hush money criminal trial wrapped up Friday.

The six alternates were finalized after 12 jurors were all seated as of late Thursday for the first-ever criminal trial of a former U.S. president.

The jury consists of seven men and five women, mostly employed in white-collar professions.

Most are not native New Yorkers, having come from across the United States and countries like Ireland and Lebanon.

They will have to decide if Trump is guilty of covering up a $130,000 payment his former lawyer Michael Cohen made to porn star Stormy Daniels before the 2016 election to keep quiet about a sexual encounter she says they had a decade earlier.

Trump has pleaded not guilty to 34 counts of falsifying business records brought by Manhattan District Attorney Alvin Bragg and has denied the affair with Daniels.

New York Law School Professor Anna Kominsky said she sees two potential hurdles for the prosecution.

"The first is they have to show that this payment was made and that it was, the entries in the Trump Organization books were false. But they also have to show that Trump knew about it. Right. So if someone did that, but Trump didn't know about that, if he didn't have this intent, he can't be found guilty. And the other thing is, because they have charged him with a felony, there's also the requirement that there be an intent to conceal another crime. And so they have to show that intent as well."

With the jury seated, opening statements in the case are expected to begin on Monday.

Trump on Friday again took issue with the gag order imposed by the judge which restricts his ability to criticize witnesses and family members of certain officials connected with the trial.

"I have a lot to say to you, and I'm not allowed to say it. And I'm the only one. Everyone else can say whatever they want about me. They can say anything they want. They can continue to make up lies and everything else. They lie. They're real scum. But you know what? I'm not allowed to speak."

Meanwhile, in a shocking development outside the courthouse later on Friday, a man set himself on fire and was taken to the hospital where he was in critical condition, according to the New York Fire Department.

He did not appear to have been targeting Trump or others involved in the trial.