President Donald Trump has called the fatal shooting of Ahmaud Arbery, an unarmed black man in the US state of Georgia, a "very disturbing situation".
Mr Arbery was jogging in February when Gregory McMichael and his son Travis, who are white, confronted him. They now face murder and assault charges.
"My heart goes out to the parents and the family and friends," Mr Trump told Fox News on Friday.
The case drew national attention when video of the death emerged on Tuesday.
Police had not charged the McMichaels for more than two months, but the pair were detained on Thursday by the state bureau of investigation.
Gregory McMichael, 64, and Travis McMichael, 34, are in the custody of the Glynn County Sheriff's Department, officials said on Friday.
Both were charged with felony murder and aggravated assault.
State investigators earlier said the father and son had followed Mr Arbery and confronted him with two firearms, and the younger McMichael shot and killed him.
Mr Arbery would have turned 26 on Friday. Rallies have taken place outside of courthouses in Glynn County and in neighbouring Jacksonville, Florida.
Online, supporters of Mr Arbery have been using the hashtag #IRunWithMaud, sharing photos and running 2.23 miles (3.6km) in remembrance of the day he died, 23 February.
What did Trump say?
Speaking on the Fox & Friends programme on Friday morning, the president said he had seen the footage, which he described as "troubling" to anyone who watched it.
Mr Trump said the state's governor and law enforcement would be looking at the case "very strongly".
When asked about the racial issues at play in the case, the president said "justice getting done is the thing that solves that problem".
"But it's a heart-breaking thing."
Ivanka Trump, the president's daughter and a White House adviser, has also weighed in, asking in a tweet "why it seemingly took months, the release of a video and corresponding public outrage to catalyse action".
At a briefing later, White House Press Secretary Kayleigh McEnany was asked whether the US Department of Justice would get involved in the case. Ms McEnany did not rule out the possibility.
A justice department spokesperson told the BBC the FBI is assisting with the investigation.
"As is standard protocol we look forward to working with them should information come to light of a potential federal violation," said the statement.
What has the family said?
"I just want justice for my son," Mr Arbery's father, Marcus, told CNN on Friday. He said the arrest was a "relief" for the family, and described his son's killing as a "lynching".
"He was a very good young man," Mr Arbery said of his son. "His heart was just bigger than life."
Benjamin Crump, a lawyer for the family, asked for the same justice for Mr Arbery as if the situations were reversed and Mr Arbery and his father had attacked an unarmed white man.
"We know beyond a shadow of a doubt they would've been arrested on day one," Mr Crump said, adding that he does not trust the local police department.
He called for the Georgia Bureau of Investigation (GBI) to investigate the officers who did not arrest the McMichaels.
"Either they were incompetent or it was intentional."
What's the status of the investigation?
GBI Director Vic Reynolds told reporters at a news conference on Friday that the McMichaels had been taken into custody without incident.
He said the investigation is ongoing. The individual who filmed the video - another local man - is also under investigation.
When asked about the previous police investigation into the case, Mr Reynolds said he could not comment, but that it had "gotten to a good point".
Mr Reynolds also noted that his agents were able to secure warrants for murder within 36 hours.
"I think that speaks volumes for itself in that the probable cause was clear to our agents very quickly."
He said in a "perfect world" his agency would have been involved back in February, but by the end of the case, "every stone will be turned over, I promise you".
On Tuesday, Atlantic Circuit District Attorney Tom Durden ruled a grand jury should consider the case and accepted Governor Brian Kemp's offer to have the GBI investigate.
.@GBI_GA Director Reynolds has offered resources & manpower to D.A. Durden to ensure a thorough, independent investigation into the death of #AhmaudArbery. Georgians deserve answers. State law enforcement stands ready to ensure justice is served. https://t.co/ktLiPf7LoY— Governor Brian P. Kemp (@GovKemp) May 6, 2020
Mr Durden is the third prosecutor involved, as two local district attorneys eventually recused themselves due to professional connections to Gregory McMichael, who is a former police detective.
Two county commissioners have told the Atlanta Journal-Constitution that in February, District Attorney Jackie Johnson did not allow police to arrest the McMichaels immediately after the shooting.
"The police at the scene went to her, saying they were ready to arrest both of them," Commissioner Allen Booker said. He claimed Ms Johnson "shut them down to protect her friend [Gregory] McMichael".
Her office has not commented to local media, and did not immediately respond to a request for comment from the BBC.
The second attorney had told police he believed the father and son had used citizen's arrest rights in confronting Mr Arbery.
The shooting has led to a wave of outrage from national figures, including presidential candidate Joe Biden and basketball star LeBron James.
Mr Biden said Mr Arbery had been "shot down in cold blood" and "essentially lynched before our very eyes".
Mr James tweeted: "We're literally hunted EVERYDAY/EVERYTIME we step foot outside the comfort of our homes!"
How did Arbery die?
Mr Arbery was out for a jog in the city of Brunswick early in the afternoon on 23 February - something his father said he did often.
Gregory McMichael told police he believed Mr Arbery resembled the suspect in a series of local break-ins.
Mr McMichael and his son armed themselves with a pistol and a shotgun and pursued Mr Arbery in a pickup truck in the Satilla Shores neighbourhood.
The elder Mr McMichael told police he asked Mr Arbery to stop and talk, and claims the 25-year-old attacked his son.
The 36-second clip appears to show the younger Mr McMichael firing a shotgun at point blank range at Mr Arbery and the victim falling to the street.