“He was saying all this stuff about how the races should be segregated, that whites should be with whites,” Mr. Meek said. “I could tell there was something inside him, there was something he wouldn’t let go. I was trying to tell him, ‘What’s wrong?’ All he would say was that he was planning to do something crazy.”

At first Mr. Meek said he did not take Mr. Roof seriously. But he became worried enough that several weeks ago he took away and hid Mr. Roof’s .45-caliber handgun, which Mr. Roof had bought with money given to him by his parents for his 21st birthday. But at the urging of his girlfriend, Mr. Meek returned the weapon because he was on probation and did not want to get into trouble…

Mr. Tyler said on another occasion, the two were driving to a strip club by the zoo when Mr. Roof saw a black woman, used a racist word and said, “I’ll shoot your ass.”

“I was just like, ‘You’re stupid,’ ” Mr. Tyler said. “He was a racist; but I don’t judge people.”