"At one point my stepfather and mother ended up having to lock up...like all the knives in the trunk of the car, just to protect everybody in the home,' Tim Hill said.
Tim Hill also confirmed that his brother threatened his life on Facebook, prompting him to call police. He said he feared for his life.
The alleged shooter's brother also expressed frustration that authorities hadn't done more to deal with his brother's mental condition before Tuesday. He said he was appreciate for what Tuff did to defuse the situation Tuesday, but doesn't believe his brother would have harmed her or the schoolchildren.
"I don't think he was there to do that," Tim Hill said of his brother. "He's always had a problem with the cops."
Police said Hill got the gun from an acquaintance, but it's not clear if he stole it or had permission to take it. His motive is still unclear.
Law enforcement officers praised Tuff for helping to avert a potential tragedy.
"She was a real ally," Alexander said. "She was a real hero in all of this. She just did a stellar job. She was cool, she was calm, very collected in all of this, maintained her wherewithal."
Tuff told WSB-TV in Atlanta that she tried to keep Hill talking to prevent him from walking into the hallway or through the school building.
"He had a look on him that he was willing to kill — matter of fact he said it. He said that he didn't have any reason to live and that he knew he was going to die today," Tuff said.
In interviews with various media outlets, Tuff has maintained that her faith in God led to a peaceful ending of the situation.
During an interview with CNN's Anderson Cooper on Thursday, Tuff said President Barack Obama called her while she sat in the network's makeup room. She described the conversation as "awesome."
She also met DeKalb County emergency dispatcher Kendra McCray, who stayed on the phone with her as she reassured Hill that surrendering peacefully was the right thing to do.
Tuff told Cooper that she'd like to visit Hill and speak with him again.
"He's a hurting soul, and so if there's any kind of way I can help him and allow him to get on the right path — we all go through something," she said during the interview.
Hill was arrested in mid-March for making terroristic threats in Henry County, DeKalb and Henry County sheriff's officials have said. He was sentenced to probation.
A woman who said she served as a mother-like figure to him said he didn't seem to have any friends and rarely talked about his family or past during the months he lived with her and her husband several years ago.
He was quiet and didn't display anger or violent tendencies, said Natasha Knotts, the woman who took him in after he started coming to the small church where her husband is pastor and she is an assistant pastor.
Knotts told The Associated Press on Wednesday that Hill lived with them for about six months in his late teens.