Roof was charged with nine counts of murder and one weapons charge. He's currently in jail.

Three days after 21-year-old Dylann Roof allegedly shot and killed nine black people during a Bible study in a historic Charleston, South Carolina, church, his apparent manifesto detailing a hatred toward black people, Jews, and Latinos appeared online.

On Monday, the Southern Poverty Law Center said Roof has been a regular commenter on The Daily Stormer, a white supremacist website.

The SPLC said that it "ran the document's full text through Grammarly, a piece of software with plagiarism detection capabilities."

The group said it found several connections between the manifesto and comments made on the Daily Stormer. Using the usernames provided by the SPLC, AryanBlood1488 and Aryan_Blood_1488, BuzzFeed News compared the comments with Roof's apparent manifesto.