One of the officials said that Roof, who is white, told investigators that he wanted to start a race war.

He himself bought the .45-caliber handgun used in the shooting last April at a Charleston gun store, according to the two officials. Earlier, a senior law enforcement official had indicated that Roof’s father bought him a Glock firearm for his birthday.

Shortly after he turned 21 in April, Dylann Roof got a gun. What’s unclear is how.

What may be getting clearer is why.