The brother of the black man fatally shot by US police this month called video of the shooting "the most horrifying thing" he has ever seen.
Michigan police this week released footage of a police officer shooting Patrick Lyoya, 26, in the head after a scuffle over a Taser.
Mr Lyoya's family, Congolese refugees, addressed media on Thursday and called for the officer's name to be released.
State police are investigating the incident, which has led to protests.
Footage of the 4 April incident in Grand Rapids, Michigan, a town some 150 miles (240km) west of Detroit, shows Mr Lyoya running from the officer following a traffic stop.
There is an altercation over the officer's Taser, before the officer appears to shoot the man as he lies face-down on the ground.
During Thursday's press conference, Mr Lyoya's father said through a translator: "My life has come to an end."
Dozens of demonstrators gathered on Wednesday outside the Grand Rapids Police Department (GRPD) demanding the name of the police officer involved be made public.
Authorities said the officer would not be identified unless criminal charges were to be brought against him.
Mr Lyoya is originally from the Democratic Republic of Congo and had lived in Grand Rapids for about five years, according to the office of civil rights attorney Benjamin Crump, who is representing the Lyoya family.
Mr Crump on Thursday said of the shooting: "There is no way to try to spin it or justify it."
He called for the officer be fired and charged.
"What you see in that video is unnecessary, unjustifiable excessive use of fatal force. You see a police officer escalate a minor traffic stop into a deadly execution," he said.
GRPD chief Eric Winstrom has called the shooting a "tragedy".