Republican Senator Bill Cassidy tweeted photos shared by US Capitol Police of an older white male with a beard wearing a blue knitted hat with “CFD” on the front.
Officer Brian Sicknick was killed when supporters of the outgoing president stormed the US Capitol to try and prevent the certification of Joe Biden’s electoral win.
"US Capitol Police just shared this picture with me. This man is wanted for questioning in connection with the murder of fallen Capitol Police Officer Brian Sicknick," Mr Cassidy tweeted.
Mr Sicknick, 42, was reportedly hit in the head with a fire extinguisher during the ugly scenes.
The 12-year force veteran collapsed after returning to his division office and was rushed to hospital, where he died from his injuries.
“Brian is a hero and that is what we would like people to remember,” his brother, Ken Sicknick, said in a statement.
He is just the sixth US Capitol police officer to die in the line of duty.
"Officer Sicknick was killed while doing his job—defending those trapped in the Capitol building amid a violent attack on our democracy," said Virginia Governor Ralph Northam after the killing.
"His death is a tragedy, and those responsible must be prosecuted to the fullest extent of the law.
“My prayers and those of the entire Commonwealth go to his family, his loved ones, and his fellow officers who work every day to protect the seat of American democracy from those who would seek to destroy it.”