"Our thoughts and prayers go out to his family, friends, and colleagues," the Capitol Police said in a statement.
"We ask that his family and other USCP officers' and their families' privacy be respected during this profoundly difficult time."
Neither statement referred to suicide, but two law enforcement officials told The Washington Post that Liebengood took his own life.
Liebengood is the second US Capitol Police officer to die after the violent storming of the Capitol building.
Brian D Sicknick was injured "while physically engaging with protesters" and succumbed to his injuries days later, one of five people to die following the day's tragic events.
One, Ashli Babbitt, was shot by police and three other rioters died after medical events.
During the struggle at the Capitol, Sicknick, 42, was hit in the head with a fire extinguisher, two law enforcement officials told the Associated Press on condition of anonymity.
The rampage that has shocked the world and left the country on edge forced the resignations of three top Capitol security officials over the failure to stop the breach.
It has led lawmakers to demand a review of operations and an FBI briefing over what they called a "terrorist attack."
Capitol Police chief Steven Sund stepped down after mounting pressure from lawmakers, issuing a statement saying police were "actively attacked" with metal pipes and other weapons.
"They were determined to enter into the Capitol building by causing great damage," Sund said, revealing that officers shot Ashli Babbitt as "protesters were forcing their way toward the House chamber where members of Congress were sheltering in place".
Where to get help:
• 0800 543 354 (0800 LIFELINE) or free text 4357 (HELP) (available 24/7)
• https://www.lifeline.org.nz/services/suicide-crisis-helpline
• YOUTHLINE: 0800 376 633
• NEED TO TALK? Free call or text 1737 (available 24/7)
• KIDSLINE: 0800 543 754 (available 24/7)
• WHATSUP: 0800 942 8787 (1pm to 11pm)
• DEPRESSION HELPLINE: 0800 111 757 or TEXT 4202
• NATIONAL ANXIETY 24 HR HELPLINE: 0800 269 4389
If it is an emergency and you feel like you or someone else is at risk, call 111.
- Additional reporting, AP