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A website featuring a 2,444-word white supremacist screed shows dozens of photos of the gunman arrested in the Charleston, South Carolina, church massacre.

The site shows a stone-faced Dylann Roof — the man who confessed to shooting nine people dead at a Bible study group, according to sources — holding weapons, visiting a cemetery for Confederate soldiers, and burning and spitting on an American flag.

Roof appears to have bought the site domain in February based on a reverse domain look-up service that found it was registered under the name Dylann Roof, using Roof's mother's home address. NBC News could not confirm the site's authenticity or whether Roof was its creator.

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Federal law enforcement sources said the FBI and local Charleston authorities have been investigating and analyzing the site, and have known about it for several days.

While the FBI is not saying with "100 percent" certainty it belongs to Roof, they are operating under the assumption that he is responsible for all of the writings, photos and other material, sources said.

One of the 60 photos on the website that was registered under Dylann Roof's name.

There are also photos on it of historic sites, such as a Confederate museum, and one picture of a beach's coastline with "1488" carved in the sand, a white supremacy encryption that stands for: "We must secure the existence of our people and a future for white children." It's unclear who took many of the photos.

In a drawn-out rant, the site's writer outlines becoming "racially aware," explaining that he wasn't raised in a racist environment, but was "awakened" by the case of Trayvon Martin, the unarmed black teenager shot to death in Florida.

The writer goes on to explain his views on race, calling black people "stupid and violent," Jewish people an "enigma," Hispanic people a "huge problem," and East Asian people "by nature very racist."

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The writer then describes a disdain for the American flag, which he says represents "people pretending like they have something to be proud [of] while White people are being murdered daily in the streets." The writer concludes by saying that he has no choice but to fight, and says he has chosen Charleston because of its historical importance and because it "at one time had the highest ratio of blacks to Whites in the country."

"1488," a numerical symbol popular with white supremacists, is carved in the sand in a photo posted to a website registered under the name of Dylann Roof.

Roof, 21, was arrested in the fatal shootings of the nine victims at the historically black Emanuel African Methodist Episcopal Church in Charleston on Wednesday night. Police say they believe the attack was a hate crime.