Large crowds are expected at Sunday's service at the black church in Charleston where nine African Americans were gunned down, as a chilling website apparently created by the suspected white supremacist shooter emerged.
The service will be the first since the bloodbath on Wednesday at the Emanuel African Methodist Episcopal Church in the southern state of South Carolina, which has fuelled simmering racial tensions in the United States and reignited impassioned calls for stronger gun-control laws.
The historic church reopened Saturday after police said it was no longer considered a crime scene, with some members visiting the room where fellow worshippers were shot dead, according to the local Post and Courier newspaper.
Meanwhile, a website allegedly created by the accused shooter, Dylann Roof, surfaced, in which the suspect rails against African Americans and appears in photographs with guns and burning the US flag.
A rambling 2,500-word manifesto on the website, laced with racist lingo and spelling errors, does not bear the 21-year-old suspected supremacist's name.
But its first-person style, its title -- "Last Rhodesian" -- and references to Charleston and apartheid South Africa suggested he was its author.
Roof, who went on the run after the shooting, was caught a day later in neighboring North Carolina and is in solitary confinement in jail charged with nine counts of murder.
The FBI said it was "taking steps to verify the authenticity" of the website.
The site emerged as grief turned to anger Saturday, with a rally at South Carolina's state legislature in Columbia where the Confederate flag has been a focal point for controversy for years.
Unlike US and state flags, it was not lowered to half-staff after the killings -- because, officials said, doing so by South Carolina law requires approval from the state legislature.
While some whites consider the Civil War-era flag an emblem of Southern pride and heritage, others -- black and white -- see it as a sinister symbol of white supremacy and racism.
Several hundred chanting demonstrators massed outside the state house, the Confederate flag flapping in the evening breeze.
Several politicians, including US President Barack Obama, weighed in on the controversy.
Former Republican White House hopeful Mitt Romney posted on Twitter: "it's time to take down flag in SC."
In response, Obama tweeted: "Good point, Mitt," with a link to Romney's comment.
Obama, who said after the Charleston shooting the United States should closely examine its gun laws, also recalled firearms deaths statistics on Twitter Saturday.
"Here are the stats: Per population, we kill each other with guns at a rate 297x more than Japan, 49x more than France, 33x more than Israel," Obama tweeted.
Roof's alleged online manifesto painted a chilling portrait of an angry young man.
"I have no choice. I am not in the position to, alone, go into the ghetto and fight," the purported manifesto stated.
"I chose Charleston because it is most historic city in my state, and at one time had the highest ratio of blacks to Whites in the country.
"We have no skinheads, no real KKK, no one doing anything but talking on the Internet. Well someone has to have the bravery to take it to the real world, and I guess that has to be me."
Downloadable files on the website contain several haunting photos of Roof, who hails from a small village outside Columbia, more than two hours by car from Charleston.
In one, he is seen in a garden, holding a Confederate flag and handgun, wearing aviator-style sunglasses and oddly surrounded by potted flowers.
Two others depict Roof in a bedroom -- one with a Confederate flag, the other pointing a handgun at the camera.
Some photos show him wearing garments with the flags of Rhodesia, as Zimbabwe was called under white rule, and apartheid-era South Africa.
On Friday, Roof appeared via videolink in court and heard devout relatives of the dead, who included Emanuel's chief pastor and state senator Clementa Pinckney, offer him forgiveness.
Later, thousands of people -- black and white -- gathered for a twilight vigil at a college basketball arena, singing the civil rights anthem "We Shall Overcome" and vowing not to let the bloodbath divide Charleston, the one-time American capital of the transatlantic slave trade.
The shooting was the worst attack on a US place of worship in decades and comes at a time of revived racial tensions in many parts of the nation.
In San Francisco, Democratic presidential hopeful Hillary Clinton called for tougher gun laws in the wake of the tragedy.
"Race remains a deep fault line in America. Millions of people of color still experience racism in their everyday lives," she said.
Authorities are treating the shooting as a hate crime and also investigating it as possible "domestic terrorism."
Roof's arrest warrant revealed how he allegedly shot the six women and three men, aged 26 through 87, multiple times with a high-caliber handgun and then stood over a survivor to make a "racially inflammatory" statement.
Roof faces the death penalty if convicted.