Trump also ordered that the flag be flown at half-staff at public buildings and military posts and vessels until January 13.
Multiple U.S. Capitol Police officers who assisted rioters at the U.S. Capitol last week have been suspended from their jobs and as many as 15 more are being investigated for their role in the riot, U.S. Rep. Tim Ryan of OH told reporters Monday.
Police identified the officer as Howard Liebengood, 51, and said he was assigned to the Senate Division.
"Our nation has a heavy heart following the deaths of United States Capitol Police Officers Brian Sicknick and Howard Liebengood", Whitmer said in a press release.
It is not clear if his death was linked to the riots, during which five people, including another Capitol police officer, died.
Police have not yet said how Sicknick was injured during the siege, which left more people dead. The cause of Liebengood's death has not been officially confirmed.
The incident in D.C., in which supporters of President Donald Trump took over the Capitol Building after a Trump rally near the White House, has led to widespread criticism against the Capitol police, as well as the resignation of its chief.
In the wake of the attack on Capitol Hill last week, and myriad questions about how rioters breached the building and what is happening in response, federal law enforcement agencies have yet to brief the public directly.
"There was a failure of leadership at the top of the Capitol Police", Pelosi said.
State and U.S. flags are at half-staff to honor U.S. Capitol Police Officer Brian Sicknick, the South River native killed during Wednesday's violent incursion by Trump supporters at the Capitol.
Northam said officer Brian Sicknick lived in Fairfax County. "The sacrifice and bravery of Officer Sicknick and his fellow officers will not be forgotten".