WASHINGTON — Jared Kushner, President Trump’s son-in-law and adviser, has added to his legal team one of the nation’s most prominent trial lawyers, Abbe D. Lowell, his lawyers said on Monday.

Mr. Kushner was already represented by Jamie S. Gorelick, a former deputy attorney general who is known for steering clients — often behind the scenes — through complicated Washington investigations.

Mr. Lowell is a trial lawyer who has represented figures from both parties in high-profile cases. His clients have included the former Democratic vice-presidential nominee John Edwards and the disgraced former Republican lobbyist Jack Abramoff. He is currently defending Senator Robert Menendez, Democrat of New Jersey, against federal corruption charges.

The Justice Department special counsel, Robert S. Mueller III, is investigating whether any of Mr. Trump’s advisers worked with the Russian government to meddle in the 2016 presidential election.