Georgia’s attorney general has asked the US Department of Justice to investigate the handling of the killing of Ahmaud Arbery, a black man who authorities say died at the hands of two white men as he ran through a neighbourhood.
Mr Arbery, 25, was killed on February 23 but no arrests were made until this month.
National outrage over the case swelled last week after video surfaced that appeared to show the shooting.
“We are committed to a complete and transparent review of how the Ahmaud Arbery case was handled from the outset,” Attorney General Chris Carr said in a statement.
“The family, the community and the state of Georgia deserve answers, and we will work with others in law enforcement at the state and federal level to find those answers.”
Several hundred people protested the case Friday in Brunswick, near the site where Mr Arbery was fatally shot.
The social justice arm of Jay-Z’s Roc Nation entertainment company on Sunday called on Georgia officials to take quick action in the case.
Shortly after the leaking of the video that appeared to show the shooting, Gregory McMichael, 64, and his son Travis McMichael, 34, were arrested and charged with murder and aggravated assault.
The arrests came hours after officials asked the Georgia Bureau of Investigation to start investigating. The inquiry was previously in the hands of local officials.
The father and son said they thought Mr Arbery matched the appearance of a burglary suspect who they said had been recorded on a surveillance camera some time before.
Mr Arbery’s mother, Wanda Cooper Jones, has said she thinks her son, a former high school football player, was just jogging in the neighborhood before he was killed.
Meanwhile, a 20-year-old man was arrested in Georgia on Sunday after an investigation into an online threat made against people protesting the killing.
The GBI said in a news release that Rashawn Smith was taken into custody in Midway, a town about 50 miles north of Brunswick, where Mr Arbery was killed.
Earlier in the day, the GBI said it “has been made aware of a Facebook post that contains a threat to future protests related to Ahmaud Arbery. We are actively investigating this situation and will provide pertinent updates as necessary.”