A $50,000 reward has been offered for the location of the 'Facebook shooter' and the hunt for him has become what Cleveland Police Chief Calvin Williams described as 'a national search."

Mr Williams said the shooter, Steve Stephens, 37, is armed "without a doubt."

Stephens filmed himself walking up to and shooting dead Robert Godwin, 74 on 16 April.

Mr Godwin was just walking down the street in Cleveland, Ohio when Stephens pulled up to him in his car and filmed the entire interaction on his phone.

Stephens did not broadcast the killing on Facebook Live but did post the video to his account, where it remained for three hours. His account was later suspended by Facebook.

Local police, in conjunction with the FBI and US Marshals Service, have expanded the manhunt beyond northeast Ohio to include the entire country.

At first the search was expanded only to include the surrounding states of Pennsylvania, New York, Michigan, and Indiana. Stephens' mobile phone signal had pinged near Erie, Pennsylvania approximately 100 miles east of Cleveland during the morning of 17 April.

Mr Williams made a public plea to "keep the [tips] coming in" even if they are from outside of the immediate Cleveland area.

"We don’t have any reason to believe he’s not in the vehicle," Mr Williams said, referring to Stephens' 2016 white four-door Ford Fiesta he was driving at the time of the shooting.

Mr Williams said procuring a new vehicle would likely require Stephens to commit a crime and police have not received any such reports.

His picture has also been widely circulated to law enforcement agencies, making buying tickets on public transportation difficult if not impossible.