Charleston Church Shooting Suspect Dylann Roof Was Apparently 'Self-Radicalized,' Investigators Say

— -- Investigators believe that the man accused of fatally shooting nine people in a historic Charleston church last week was "self-radicalized," according to a law enforcement official briefed on the investigation.

Probers are continuing to piece together Dylann Roof's steps -- in real life and online -- in the days leading up to the shooting, the official said.

As of now, it appears that Dylann Roof was "self-radicalized," meaning that he was not believed to be part of a hate group, and acted alone as well.

That hasn't stopped investigators from serving subpoenas to internet and telecommunications companies. In doing so, it will allow investigators to recreate the 21-year-old's entire digital footprint.

The news of these subpoenas comes one day after authorities confirmed to ABC News that they are investigating a website that contained his purported manifesto and pictures of him at times holding a gun or a Confederate flag.

Among prognostications about segregation and other racist topics, the writer says "someone has to have the bravery to take it to the real world, and I guess that has to be me.”

Investigators have not made a final determination on the authenticity of the manifesto and photos but are working under the belief they're as real as they appear to be, a federal official briefed on the probe told ABC News.

Roof is being held at the Al Cannon Detention Center in Charleston and has been charged with nine counts of murder as well as a weapons charge. He has not yet had to enter a plea.

ABC News’ attempts to reach Roof’s lawyer have gone unanswered.