A picture is beginning to develop of the life of Roof and his motivation for church attack that left nine people dead.
Hundreds of people have flocked to Emanuel African Methodist Episcopal Church in Charleston, in the US city of South Carolina, after it reopened its doors to worshippers, four days after a white man shot nine black church members to death.
Sunday morning marked the first worship service at the church since Dylann Roof, 21, sat among a Bible study group and opened fire on Wednesday after saying that he targeted them because they were black, authorities said.
“It has been tough, it’s been rough, some of us have been downright angry, but through it all God has sustained us and has encouraged us,” said the Reverend Norvel Goff, who was appointed pastor to replace Rev. Clementa Pinckney, a state politician, who was among those people killed.
Al Jazeera’s Gabriel Elizondo, reporting from Charleston, described a “very emotional” church service attended by an estimated 2,000 people.
Church attendees sang gospel songs as thousands more gathered outside to show their solidarity following the shooting.
“They are trying to do the best out of a very difficult situation,” our correspondent said.
Outside the church, the oldest African-American congregation in the southern US, bouquets, bears and balloons covered the pavement while hundreds of people lined up to mourn, sing hymns and leave memorials.
One of the victims, Senator Pinckney, will be buried on Friday. The funeral will be held at TD Arena on the College of Charleston campus, a funeral home spokesperson confirmed the details to The State newspaper.
The FBI said it was investigating a manifesto purportedly written by Roof.
The website linked to Roof contained photos of him holding a burning American flag and standing on one.
In other images, he was holding the Confederate flag representing the pro-slavery South in the American Civil War, considered a divisive symbol by many.
Roof is being held in jail, facing nine counts of murder and a weapons charge.
Meanwhile, there are growing calls for the removal of a Confederate flag from the grounds of the South Carolina Statehouse.
A Republican state legislator said he would introduce a bill in December to move the flag and pole to a state military museum.
A large crowd rallied in Columbia on earlier on Sunday to protest against the presence of the flag, calling it a symbol of hatred, not heritage.