The trial in the New York criminal case against Donald Trump begins Monday with jury selection, the first of the four criminal cases against the former president to reach this pivotal stage.

The charges against Trump stem from an investigation by the Manhattan District Attorney’s office into an alleged “catch and kill” scheme to bury negative stories about Trump before the 2016 presidential election in a bid to influence the outcome.

According to prosecutors, several people participated in the scheme, which involved paying people off to buy their silence and covering up the payments in Trump’s business records.

Here are the key people in the case who will come up during the trial, potentially as witnesses: