The rostrum where Clerk Bruce F. Jamerson stood day after day for two decades watching over the Virginia House of Delegates was covered with a black shroud Monday. No one stood behind it.

One by one, delegate after delegate stood up on the House floor in the Capitol designed by Thomas Jefferson, their eyes tearing up and voices breaking, to pay tribute to Jamerson, the chamber’s chief historian and protector of its traditions.

Jamerson’s body was found Monday beside the James River in Powhatan County. He died of a self-inflicted gunshot wound to the head, officials said. He was 53.

“Jefferson himself could not have loved this place more than Bruce Jamerson,’’ said House Minority Leader Ward L. Armstrong (D-Henry), pausing occasionally to collect himself. “He loved his wife. He loved his family, but he was immersed in the House of Delegates. It was in the very fabric of his being.”

Jamerson’s death — and its cause — shocked the state’s political leaders. Condolences poured in from former governors, members of Congress and, of course, the legislators he served every day in line with the job’s official title: Clerk of the Virginia House of Delegates and Keeper of the Rolls of the Commonwealth.

“Bruce Jamerson was a State Capitol institution,” Gov. Robert F. McDonnell (R) said. “His was a life of substance, character and meaning. . . . Our memories of him will be forever cherished.”

McDonnell ordered the state flag over the Capitol to be lowered to half-staff Monday and Tuesday.

A nonpartisan employee of the legislature, the clerk, along with staff members, track and organize thousands of bills filed by the House. During hours-long floor sessions, the clerk stands just beneath the House speaker, reading aloud bill numbers and votes.

In the House, already scheduled to convene Monday for a special session on redistricting, all official business stopped for more than an hour as delegates gave a passionate tribute to Jamerson. Dozens of staffers from both chambers circled the floor, many crying.

They swapped stories about how he always remembered to send birthday cards, usually with a “Peanuts” theme, how he led their out-of-town guests on tours of the Capitol whose renovation he helped lead, and that he mentored thousands of students through Boys State and Model General Assembly.

“Bruce embodied so much of what is good and noble about public service,” House Speaker William J. Howell (R-Stafford) said.

Jamerson had served the House for 38 sessions. In recent weeks, he had been in Richmond as legislators began debating redistricting, and had returned Saturday from a Mediterranean cruise with his family.

Police were contacted late Sunday night to search for Jamerson. They found his abandoned car at Watkins Landing along the James River, according to a statement issued Monday by the Virginia State Police.

At about 2:30 a.m. Monday, a State Police bloodhound located Jamerson’s body along a path near the river. The cause of death was confirmed by the Office of the Chief Medical Examiner. The Washington Post generally does not report on suicides, except in cases of public figures whose deaths would be newsworthy under any circumstance.

Legislators reacted to the news of Jamerson’s suicide with confusion and sorrow, saying it reminded them that people, even friends and colleagues, sometimes hide their troubles.

“I don’t know why we couldn’t hug him enough, but he was a beautiful person,’’ Del. Vivian E. Watts (D-Fairfax) said. “Please, if you need help, go, because we can’t afford to lose another beautiful person like Bruce.”

Jamerson spent his entire professional life in the House of Delegates, first coming to work in the clerk’s office as a junior in high school after he learned about the legislature’s page program, geared to middle school students, when he was too old to participate.

He was widely acknowledged to be an expert in the history of the House, the oldest continuously operating legislative body in the Western Hemisphere. His phone extension at the Capitol, famously, was x1619, the year of the first meeting of the Virginia House of Burgesses, and he guarded zealously the Capitol’s traditions.

As House clerk, Jamerson helped lead the renovation of the Capitol that concluded in 2007, working to ensure that the building was restored authentically, even as it gained a modern underground visitor’s center.

Along with delegates, he met with the Queen Elizabeth II when she visited Virginia that year and worked closely with British officials to ensure proper protocol was observed for the visiting monarch.

Every four years, he donned a gray morning coat and white gloves and presided over the inauguration of Virginia’s governor. The traditional suit was so important to him that he at first refused to wear a top coat for the inauguration of Gov. George F. Allen (R) in 1994, a famously frigid Richmond day.

“I had to tell him, ‘It’s not going to do anyone any good if you get pneumonia,’ ” said Jamerson’s counterpart in the Senate, Susan Schaar, who met Jamerson in 1974. “He wanted to look appropriately attired.”

As House clerk, Jamerson occasionally found himself at the center of the partisan wrangling. In 1998, Jamerson briefly took control of the House, issuing the parliamentary rulings usually reserved for the speaker when a chamber closely divided between Republicans and Democrats could not agree on a power-sharing arrangement and the body was briefly left without a leader. Before the incident and after, he always earned high marks for fairness from both sides of the aisle. First named clerk under Democratic control, he kept the job after Republicans took over the chamber.

“When you put the institution first, you rise above the partisan bickering,” Schaar said.