Malcolm Graham, whose sister, Cynthia Hurd, was one of the nine people fatally shot by Roof during a Bible study class at the Emanuel African Methodist Episcopal Church in June 2015, told CNN's Carol Costello that for him, the appropriate sentence in this case is crystal clear.
"If there's any case in America where the death penalty is deserved, it is this one," Graham said.
"The crime was premeditated. It was calculated."
But most importantly, Graham said, Roof's crime "was an attack on a race of people."
"Those who died that night simply died because they were there, and that they were black. That type of hate, that type of discrimination, that type of just evil, has no place in a civilized society, and has no place in America's jails," he emphasized.
Roof, who confessed to the killings, was found guilty of all 33 federal counts against him on Thursday.
Next month, the jury will decide whether to sentence him to death. The self-declared white supremacist, whose lawyers have challenged the federal death penalty, will represent himself
in the penalty phase of the trial. That means that he'll have the right to pose questions to the relatives of those he murdered. It's a nightmare scenario that Graham, nonetheless, is determined to be a part of; for the sake of the woman he called a "mentor and a mother figure."
"She was personable. She was sharp. She was candid. She loved life. She loved her community," Graham said.
"Not only was she a big sister to me, but she was a role model. So the community lost a community asset that night. And if called upon to tell the community who Cynthia was, and how she lived, and what type of loss the Charleston community has suffered because of her death, I'm well prepared to do that," he added.
As for what he would say directly to the man who killed his sister, Graham told Costello he had words prepared.
"I will say that he's an evil killer. That he's a coward," he said.
"He's a racist. There's no place in a civilized society for him and there's no place in America's smallest jail for him."