WASHINGTON — When the curtain rises on the first formal day of televised impeachment hearings into President Trump, members of the House Permanent Select Committee on Intelligence will be seated on the dais, questioning witnesses alongside the lead Democratic and Republican investigators. The committee, affectionately known on Capitol Hill by its acronym, HPSCI (pronounced “hip-see”), is charged with overseeing the nation’s intelligence agencies, and has been leading the closed-door impeachment inquiry. The panel has 22 members — 13 Democrats and nine Republicans. Here’s a look at some of the key members.

Adam B. Schiff, Democrat of California and the chairman of the committee

Mr. Schiff, a strait-laced former federal prosecutor, has been leading the inquiry, drawing condemnation from Mr. Trump, who refers to him on Twitter as “Shifty Schiff.” A lawyer educated at Stanford University and Harvard Law School, Mr. Schiff, 59, has been the subject of attacks from Republicans who say he is running an unfair process. Methodical, measured and unflappable, he has cast himself as the anti-Trump, and he is aiming to run a solemn process. He has deep experience in questioning witnesses; he tried his first big case three decades ago when, as a young federal prosecutor in Los Angeles, he secured the conviction of an F.B.I. agent who was seduced by a Soviet spy and traded secrets for gold and cash.