President Donald Trump’s Senate impeachment defense team will include Ken Starr, whose investigation led to the impeachment of President Bill Clinton, and Harvard law professor Alan Dershowitz. Dershowitz’s role on the team will focus on the constitutional arguments against impeachment, the team said Friday. The law professor is known to have represented notorious sex offender Jeffrey Epstein and O.J. Simpson.

Trump’s selection comes as the president’s impeachment trial is set to begin Tuesday in the Senate. He is accused of abusing his power by pressuring Ukraine to investigate former Vice President Joe Biden and his son Hunter last summer and withholding military aid until it did so. Lawyer Robert Ray, who succeeded Starr as independent counsel in the Whitewater investigation, is also expected to join the defense team.

“While Professor Dershowitz is nonpartisan when it comes to the Constitution—he opposed the impeachment of President Bill Clinton and voted for Hillary Clinton—he believes the issues at stake go to the heart of our enduring Constitution,” the team said in a statement.

A Fox News spokesperson confirmed to The Daily Beast that Starr is no longer a network contributor.