(CNN)Joey Meek, a friend of confessed Charleston church shooter Dylann Roof, was arrested by the FBI on Thursday, a law enforcement official said.

It was not immediately clear what charges Meek faces.  Authorities have been investigating Meek since the June shooting for allegedly knowing about the crime and not telling authorities, the official said.

In the days after the shooting, Meek spoke with reporters with CNN and other media outlets, recounting how Roof had drunkenly vowed one night "to do something crazy."

Meek said he hid Roof's gun that night, but put it back the next day.

"I didn't take him serious,' he said.

After hearing the description of the suspect in the Charleston church shooting, Meek told CNN he called the FBI the next morning, giving authorities detailed descriptions of what Roof was wearing and the license plate on his car.

Roof, 21, faces state and federal charges for the June 17 deadly attack at Charleston's Emanuel African Methodist Episcopal Church.

If convicted, he could face the death penalty.

Nine people were killed in the Bible study massacre, including the Rev. Clementa Pinckney, who also was a state senator.

Roof was captured in North Carolina the day after the attack and was brought back to South Carolina. Law enforcement officials have said he admitted to the killings.

Meek told CNN shortly after the shooting that he had been friends with Roof in middle school. They'd lost touch a few years ago, but reconnected in recent months, Meek said, adding that there were things about Roof's recent behavior that scared him.

Roof said he wanted to have "a race war," according to Meek, and once asked his friend to videotape him burning an American flag.

"I'm sorry this all happened to everybody," Meek said in June. "And it could have been prevented if people would have taken him serious. But Dylann wasn't a serious person, and no one took him serious."