A trial to determine if Google abused its monopoly in online search, which begins on Tuesday, is set to lay bare how the internet search giant cemented its power, featuring testimony from top tech executives, engineers, economists and academics.

The trial will unfold in U.S. District Court for the District of Columbia, where a core group of individuals will command the courtroom and direct the day-to-day legal strategies. Here are the key people to know in U.S. et al. v. Google:

Judge Mehta, who was appointed to the bench in 2014 by President Barack Obama, will referee and decide the case in the nonjury trial.

In more than three years of pretrial hearings, Judge Mehta hasn’t tipped his hand on his views of the case. In a proceeding last month, he narrowed the lawsuit by the Justice Department and states while preserving the core argument that Google maintained its monopoly in search through deals with smartphone makers that cut out competitors.

Judge Mehta, 52, was randomly assigned to U.S. et al. v. Google. He may be more familiar with Google than other federal judges, whose average age reached 69 in 2020, according to a study at the time by The Ohio State Law Journal. He received his law degree from the University of Virginia in 1997, a year before Larry Page and Sergey Brin founded Google.

Judge Mehta previously worked in private practice in San Francisco and Washington, focusing on white-collar criminal defense, complex business disputes and appellate advocacy.

Mr. Kanter, the top antitrust official at the Justice Department, is overseeing the government’s case.

President Biden appointed Mr. Kanter, a longtime tech and media lawyer who received his law degree from Washington University in St. Louis, to the Justice Department in July 2021. Mr. Kanter is among a group of progressive Big Tech critics whom Mr. Biden has placed in top government positions for antitrust enforcement. He inherited the Google case from the Trump administration.

Mr. Kanter, 50, is also overseeing a separate antitrust lawsuit against Google in the ad tech market. Google has raised concerns that his history of representing its rivals, including Microsoft and News Corp, makes him biased, and the company has protested his involvement in the ad tech case.

It’s unclear how often Mr. Kanter will appear in court. Doha Mekki, the Justice Department’s principal deputy assistant attorney general, and Hetal Doshi, the deputy assistant attorney general for antitrust, have helped quarterback the lawsuit and will be in the courtroom daily.

Mr. Dintzer, a 30-year veteran of the Justice Department, will give opening statements and is leading the government’s case in the courtroom.

A graduate of the University of Michigan law school, Mr. Dintzer, 59, was assigned to the Google case during the Trump administration. He has argued in pretrial hearings before Judge Mehta that Google destroyed instant messages “depriving” the department “of a rich source of candid discussions between Google’s executives, including likely trial witnesses.”

He has worked on antitrust cases in the past, including the Justice Department’s lawsuit to block AT&T’s proposed merger with T-Mobile in 2011. The companies eventually dropped the deal.

Mr. Weiser is overseeing a coalition of 38 state and other attorneys generals that joined the Justice Department in its search lawsuit.

Mr. Weiser, 55, a former deputy assistant attorney general of antitrust at the Justice Department for the Obama administration, has been a vocal critic of big tech companies for stifling competition. After graduating from New York University Law School, he became a counsel to Joel Klein, the Justice Department’s head of antitrust during the agency’s Microsoft monopoly lawsuit in the 1990s. He didn’t work directly on the case but said in an interview that it had influenced him.

Mr. Weiser has picked John Sallet, a former deputy head of antitrust at the Justice Department, and William Cavanaugh, a lawyer at Patterson Belknap Webb & Tyler and a former Justice Department official, as the lead litigators for the states.

Mr. Pichai, the chief executive of Google, is widely expected to testify during the trial.

He joined Google in 2004 as a product management leader of Chrome and other tools, and was named chief executive in August 2015.

A measured and calm speaker who has at times been called boring, Mr. Pichai, 51, was largely unruffled when testifying in congressional hearings over content moderation and antitrust in recent years. That may serve him well in the trial.

Google’s founders, Mr. Page and Mr. Brin, aren’t expected to be called as witnesses. But the Justice Department and Google are likely to call other tech executives to testify, including Eddy Cue, Apple’s senior vice president of services, to discuss the company’s search deals with Google.

Mr. Walker, Google’s president of global affairs and chief legal counsel, is overseeing the company’s defense.

Mr. Walker, 62, received his law degree from Stanford and joined Google in 2006. He led Google’s policy and legal strategy through an antitrust investigation by the Federal Trade Commission that began in 2009. The agency decided not to proceed with a lawsuit after the company agreed to some changes.

Mr. Walker is overseeing a big team of in-house and outside lawyers and will be in and out of the courtroom. Google’s daily legal representative in the courtroom, who has supervised strategy on the case, is Lara Kollios, a director in regulatory response and investigations.

Mr. Schmidtlein, a co-chair of antitrust at Williams & Connolly, is Google’s lead lawyer in the courtroom.

Google has turned to lawyers like Mr. Schmidtlein, 57, who fought against Microsoft in antitrust cases two decades ago, to defend it in court. In 2002, Mr. Schmidtlein represented states that sued Microsoft for using its dominance in Windows software to block rival media players.

Mr. Schmidtlein, who received his law degree from Georgetown University, also has a long track record working for tech companies. This year, he helped Amazon defeat an antitrust lawsuit that consumers brought against its logistics practices.

Google’s litigation team also includes Susan Creighton, a partner at Wilson Sonsini Goodrich & Rosati who represented Netscape in the government’s 1998 antitrust suit against Microsoft, and Mark Popofsky, a partner at Ropes & Gray who was a senior counsel to the Justice Department in that suit against Microsoft.