The 2,000-word text explains the writer's philosophy of white superiority, saying the Trayvon Martin case "truly awakened me" and that "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."
Motive has become the biggest question as state and federal investigators work on the case -- and statements and photos on the website match what investigators have determined so far.
For instance, CNN Charlotte affiliate WBTV, citing a source, says Roof told investigators in Shelby, North Carolina, where he was arrested, that he researched the church and targeted it because it turned out to be a "historic African-American church."
Three photos show Roof posing with a pistol. One closeup shows a gun that can be identified as a.45-caliber Glock -- the model of gun investigators say was used in the church shooting. Those photos were taken in April, after his 21st birthday, when his family said he purchased a .45-caliber gun.
The website, called the Last Rhodesian, is bare bones. Roof's name doesn't appear anywhere on the site but he is shown in many of the photos.
An Internet ownership search shows the website was registered to Roof and listed as the administrator. The ownership search listed not only Roof's name, but his address in South Carolina, his email and his phone.
The website was registered in February but surfaced on Twitter and other social media Saturday.
The FBI and Charleston police are looking at this document to see whether it is Roof's, according to a posting on the Charleston police verified Twitter account
. So far there's no evidence the attack was directed by a white supremacist group, a law enforcement official told CNN.
The name "last Rhodesian" is apparently a reference to the former British colony in Africa that was ruled by a white minority until it became independent in 1980 and changed its name to Zimbabwe.
One of the photos on the website shows Roof wearing a jacket with a flag of Rhodesia as well as one of apartheid South Africa. The white supremacist movement venerates both governments.
Roof confessed to the shootings in interviews with the Charleston police and FBI, two law enforcement officials told CNN.
"Whites" always capitalized
The writer of the text explains how he or she came to believe that whites -- a word he always capitalizes -- are superior to other races.
"I was not raised in a racist home or environment. Living in the South, almost every White person has a small amount of racial awareness, simply beause (sic) of the numbers of negroes in this part of the country."
The writer says blacks have a racial awareness, which is something whites need to develop. He says segregation was a good thing because it protected whites from blacks and integration is bringing whites down to the level of blacks.
He discusses Jews and Hispanics in derogatory terms but says he respects East Asians because they could be "allies" to whites.
The writer says the Trayvon Martin case "truly awakened me." Martin was a black Florida teen fatally shot in 2012 by George Zimmerman, who was acquitted in court.
"I kept hearing and seeing his name, and eventually I decided to look him up," the text says. "I read the Wikipedia article and right away I was unable to understand what the big deal was. It was obvious that Zimmerman was in the right."
In a statement, Benjamin Crump, lead attorney for Martin's family, said "it is not uncommon for those who commit unspeakable acts of violence to blame their heinous behavior on the actions of others."
"Regardless of how this demented, racist individual attempts to shift the focus of his murderous actions, we will remain steadfast in our defense of the voiceless around this country," the statement said. "They need it now more than ever."
The writer says he looked up "black on White crime" on the Internet.
'I have no choice'
"I have never been the same since that day," he said.
Near the bottom of the manifesto, the writer says:
"I have no choice. ... 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. ... Well someone has to have the bravery to take it to the real world, and I guess that has to be me."
It's not clear who took any of the 60 photos, which were shot between August 3, 2014, and June 17, with the majority shot in March and April. Roof appears alone in many of them, never smiling. The other pictures show objects or landscapes and no other people.
Photo of gun with laser sight
The pictures of the .45-caliber Glock handgun posted on the website show Roof had installed a Sig Sauer compact pistol laser on the weapon. The laser-targeting device, which sells for about $100, mounts under the front of the gun's barrel.
In one of the images where Roof is seen pointing the gun directly at the camera, the laser appears to be illuminating.
Authorities have said Roof used a .45-caliber Glock model 41 in the attack at Emmanuel Church. The pictures posted to Roof's website match that model. Police have not mentioned whether the weapon was equipped with a laser-targeting device and it is not known whether the laser device was actually used in the attack. Such a device would have made aiming the weapon much easier.
One picture shows Roof sitting on a low chair in what looks like a back yard with potted flowers on both sides and in front of him. He gazes into the camera over sunglasses that have slipped down to the end of his nose while holding a pistol in one hand and a small Confederate flag in the other.
Roof waves Confederate flag
Photos taken May 11 show Roof burning and spitting on an American flag. Another May 11 photo shows him holding a small Confederate flag.
Other pictures could have been taken of anybody visiting tourist sites around Charleston. Many were taken the same day and touch on issues of slavery and the Confederacy.
He's photographed at Boone Hall Plantation, a former rice plantation open for tours; beside the Angel Oak, an ancient and massive tree; beside an informational sign for Sullivan's Island, where thousands of slaves were off-loaded; and at the entrance to an African-American cemetery. The entrance to a Confederate cemetery is pictured.
He also poses outside the Museum and Library of Confederate History in Greenville.
One picture shows Roof crouching on the sand, apparently at the beach, with the numbers "1488" drawn in the sand.
The Southern Poverty Law Center says
those digits refer to a 14-word slogan coined by David Lane, who was convicted in the killing of a Jewish talk show host, and that 88 means "Heil Hitler." H is the eighth letter of the alphabet.