A second Capitol Police officer has died just days after the US Capitol building was breached on Jan. 6, according to the Capitol Police.

The federal law enforcement agency confirmed the Jan. 9 death of Officer Howard Liebengood, 51, who worked with the US Senate.

"The United States Capitol Police is deeply saddened by the off-duty death of Office Howard Liebengood, age 51. He was assigned to the Senate Division, and has been with the Department since April 2005. Our thoughts and prayers go out to his family, friends, and colleagues. We ask that his family, and other USCP officers' and their families' privacy be respected during this profoundly difficult time."

The cause of death was an apparent suicide, according to several sources. It remains unclear whether his death is connected to the Capitol riots - which led to the death of a Capitol Police officer.

Capitol Police union chair Gus Papathanasiou released a statement praising Liebengood's service.

"We mourn the death of a friend and colleague who worked alongside us to protect the lives of the Members of Congress, their staff and all who serve at the US Capitol," he wrote. "He was among the officers who responded to the rioting at the US Capitol on January 6. We pay tribute to his service and we grieve for the loss of a fellow officer."

He added: "Every Capitol Police officer puts the security of others before their own safety and Officer Liebengood was an example of the selfless service that is the hallmark of USCP. This is a tragic day."

On Jan. 7, Capitol Police Officer Brian D. Sicknick passed away from injuries suffered during the riots the day before.

Rioters angered by President-elect Joe Biden's victory over President Donald Trump breached the historic building, causing lawmakers to flee the Electoral College certification of Biden's win and left five people dead, including Officer Sicknick.