WASHINGTON — U.S. Capitol Police on Sunday announced the death of off-duty officer Howard Liebengood, the son and namesake of a former Senate sergeant at arms, lobbyist and Hill staffer.

Two law enforcement officials told The Washington Post that Liebengood, 51, died by suicide over the weekend, days after being on the scene of Wednesday’s violent siege of the Capitol building by a pro-Trump mob.

Statements released Sunday by the Capitol Police and its union did not specify a cause of death for Liebengood, who had been with the department since April 2005 and was assigned to the Senate Division. A former co-worker said he was often assigned to the Delaware entrance of the Russell Senate Office Building – his favorite posting.

“We are reeling from the death of Officer Liebengood,” Gus Papathanasiou, head of the Capitol Police union, said in a statement, adding: “Officer Liebengood was an example of the selfless service that is the hallmark of USCP.”

The statement from the Capitol Police says: “Our thoughts and prayers go out to his family, friends, and colleagues.”

On social media, there was an outpouring of grief for Liebengood. Rep. Jennifer Wexton, D-Va., posted on Twitter that she was “deeply saddened” over the death of her constituent.

“Officer Liebengood served with USCP for 15 years, continuing a family tradition of protecting the U.S. Senate,” she wrote. “My heart breaks for his family, his loved ones, & our community.”

Former senator and secretary of state John Kerry, D-Mass., tweeted: “During my last years in office, Howie was stationed next to one of our offices in the Russell Building – doors where everyone from school groups to protesters entered/exited. . . . Howie always had a smile on his face, but he also showed great care for the safety of the young staff who worked behind our office doors.”

Barry Pollack, a lawyer who said he is representing the Liebengood family, said in a statement that “Mr. Liebengood’s family members wish to grieve privately as they mourn the sudden and heartbreaking loss of Howard Liebengood.”

“He will be sorely missed,” the statement added. Liebengood is survived by his wife and siblings.

Friends described Liebengood as humble and reserved, and said he shared a love of racecar driving with his father, as well as a pull toward the halls of the Capitol. He spent several years as a professional racecar driver until 2005, when he left the profession to become a Capitol Police officer.

Charlie Ostlund, 70, taught Liebengood at James Madison High School in Vienna, Va., in the 1980s, and was his wrestling coach. He remembered Liebengood as a team player who often surprised opponents with his strength and physical talent.

Ostlund said the younger Liebengood looked up to his father, Howard S. Liebengood Sr., who served as the Senate sergeant at arms from 1981 to 1983. The sergeant at arms is the chief law enforcement officer of the Senate, charged with ensuring security in the Capitol and Senate buildings, as well as protecting members of the Senate.

In a 2003 interview with a motorsports website, the younger Liebengood said his parents were his biggest inspiration. My father “has accomplished so much in his professional career in government and the political arena,” he said at the time. “If I could accomplish an [eighth] of what he has accomplished, I would be very proud . . . he is my hero!”

Liebengood told his interviewer he was involved in the National Campaign to Stop Violence, an effort aimed at middle-schoolers.

“He was a great student and great kid,” Ostlund said. “This is just so, so sad.”

Liebengood Sr. left his post as sergeant at arms to become a lobbyist, eventually starting his own firm with another former Hill staffer. In 2001, he returned to Capitol Hill as chief of staff to his longtime friend Sen. Fred Thompson, R-Tenn., and later to Senate Majority Leader Bill Frist, R-Tenn. He died of a heart attack on Jan. 13, 2005, two weeks shy of his planned retirement.

Frist spoke about Liebengood Sr. on the Senate floor after his death, according to a 2005 Senate transcript: “Howard Liebengood loved the Senate,” he said. “He loved the purpose of this institution; he loved its tradition; and, above all, he loved its people. The Senate was his extended family.”

A classmate and wrestling teammate of the younger Liebengood, Stu Wilkinson, said his friend’s relationship with Washington’s political elite dates back to their childhood – though he did not brag about it.

He recalled a school trip to the White House in the 1980s, when Secret Service officers took Liebengood aside to have him speak with then-Senate Majority Leader Howard Henry Baker, R-Tenn.

“Here comes Senator Baker shaking Howie’s hand,” Wilkinson said. “[Liebengood] was so humble. . . . None of us had any clue how they knew each other.”

Wilkinson said that when he saw news reports of the Capitol riots on Wednesday, his mind went straight to Liebengood. He scanned the television footage, hoping his friend was all right.

“He was an outstanding guy,” Wilkinson said. “A quiet, silent leader.”

Bill Beck, 80, was a close friend of Liebengood Sr. who watched his son grow up. At the Capitol, he said Sunday, both men strove to engage lawmakers and staffers regardless of political party.

On the day of the Capitol attack, Beck said he emailed the younger Liebengood to see how he was doing. He did not hear the news of his death until Sunday.

“I knew him his whole life. He was a good human being,” Beck said. “After everything, this is just . . . it’s tragic.”