Associates of Dylann Roof have reportedly become "persons of interest" in the joint state and federal investigation centered on the 21-year-old accused of carrying out the mass shooting last month at a church in Charleston, South Carolina. The State newspaper in Columbia, South Carolina, reported the probe now encompasses associates of Roof who may have had knowledge of his alleged plans, with the paper citing "multiple sources familiar with the ongoing investigation."

Roof has been charged on multiple counts of murder in the shooting that killed nine black people at the Emanuel African Methodist Episcopal Church in Charleston June 17. The alleged actions by Roof, who is white, appeared to be racially motivated. A website, purportedly created by Roof, surfaced online and contained a manifesto detailing its author's racist beliefs. The site also featured photographs of Roof holding weapons and posing with a Confederate flag.

The State reported that while Roof apparently traveled alone to and from Charleston on the day of shootings, its sources said it is possible others had knowledge of his plans. The sources reportedly asked to not be identified because they were not authorized to speak publicly about the investigation.

Computer and phone records led investigators to look into how much Roof's associates knew and when they knew it, sources told the State. The newspaper did not report who the associates are, but it did say that sources told it prosecutors are deciding which charges -- if any -- those associates might face. Possible charges reportedly include misprision of a felony and lying to a federal law enforcement officer. Misprision of a felony means having knowledge of an impending crime, but not informing authorities, effectively concealing the crime. 

Roof faces nine counts of murder and a weapons charge in South Carolina's General Sessions Court, and he reportedly could face hate-crime charges on the federal level.

"As the Attorney General [Loretta Lynch] said, 'We have opened a file on this and are continuing to investigate this tragedy,'" the State quoted U.S. Attorney Bill Nettles as saying Thursday.

Roof is being held in the Charleston County jail after a June 19 bond hearing that set a $1 million bond on the weapons charge and no bail on the nine counts of murder. Roof was arrested shortly after the mass shooting, and authorities say he confessed to the killings, as the State reported.