Natasha Knotts told The Associated Press that Michael Brandon Hill lived with her and her husband for a time when he was in his late teens. She says she served as a mother figure for Hill in after he started coming to the small church where she and her husband are pastors.
Also on Wednesday, police gave more details about the ordeal and what led up to it. Before going to the school, investigators say that Hill took a photo of himself with an AK 47-style rifle and packed up nearly 500 rounds of ammunition - enough to shoot more than half the school's students.
Police said Hill got the gun from an acquaintance, but it's not clear if he stole it or had permission to take it.
No one was injured, but the suspect exchanged gunfire with police who surrounded Ronald E. McNair Discovery Learning Academy in Decatur. The school's 870 students in pre-kindergarten through fifth grade were evacuated.
"We have to make a reasonable assumption he was there to do harm to someone," said DeKalb County Police Chief Cedric L. Alexander.
Knotts said Hill called her sister Tuesday afternoon before the shooting and said he had a rifle but didn't say what he was planning to do. She said she believes that Hill acted out as a plea for help.
"This is something that's totally out of his character. This is not him. This is not the Mike that I know. For anyone that knew Mike, this was a total devastation," she said in an interview at her home in Lithonia.
Knotts said she thinks of herself as the 20-year-old Hill's adoptive mother. Hill told her that his birth mother was dead and that he didn't know his father. He also has a brother.
Hill held one or two staff members in the front office captive for a time, the police chief said, making one of them call a local TV station. At some point, he fired into the floor of the school office. As officers swarmed the campus outside, he shot at them at least a half a dozen times with an assault rifle from inside the school and they returned fire, police said. Police came into the school office, and Hill surrendered.
Hill is charged with aggravated assault on a police officer, terroristic threats and possession of a firearm by a convicted felon. Police questioned him for hours at headquarters, but declined Wednesday to discuss what he said.
DeKalb County Police Detective Ray Davis said a court date could take place in the coming days.
Davis said Hill's motive was unclear but he'd had contact with the school office before. Hill had an address listed in court records about three miles from the school in Decatur, but no clear ties to the school.
The ordeal terrified parents.
Rufus Morrow was at work when he got a phone call with news that shots had been fired at the school his daughter attends.
He drove "about 90 mph" to the school. The police chief says Hill, armed with an assault rifle and other weapons, was able to slip into the school where visitors must be buzzed in by staff.
Morrow said he almost cried as he told his supervisor why he needed to leave.
"Just the mere thought of what happened at that other elementary school happening here, it was just devastating to my soul," he said, referring to the Sandy Hook Elementary School massacre in Connecticut in December that left 26 people dead, 20 of them children.
School bookkeeper Antoinette Tuff says she was one of the employees held hostage.
In an interview on ABC's "World News with Diane Sawyer," Tuff said she worked to convince the gunman to put down his weapons and ammunition.
"He told me he was sorry for what he was doing. He was willing to die," Tuff told ABC.
Speaking Wednesday on ABC's "Good Morning America," Tuff said the suspect told her he hadn't taken his medication.
She told him her life story, about how her marriage fell apart after 33 years and the "roller coaster" of opening her own business.
"I told him, 'OK, we all have situations in our lives," she said. "It was going to be OK. If I could recover, he could, too."
Then Tuff said she asked the suspect to put his weapons down, empty his pockets and backpack on the floor.
"I told the police he was giving himself up. I just talked him through it," she said.
She 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, adding that Hill told her he was sure he'd be killed because he'd shot at police officers. "I knew that if he got out that door he was gonna kill everybody," she said.
Dramatic television footage showed lines of young students racing out of the building with police and teachers escorting them to safety. They sat outside in a field for a time until school buses came to take them to their waiting parents and other relatives at a nearby Wal-Mart.
Morrow was one of those parents and held his 10-year-old daughter close to him during an interview after the two were reunited.
"My stomach was in my throat for the whole time until I saw her face on the bus," he said.
His daughter, a fifth-grader named Dyamond, told The Associated Press that a voice came over the intercom saying school was under lockdown and instructed students to get under tables. She said her teacher told the class to sing and pray.
"There were a lot of girls crying, I was feeling scared but I didn't cry. I was just nervous," she said.
Tuff called WSB-TV as it was happening to say the gunman asked her to contact the Atlanta station and police. WSB said during the call, shots were heard in the background. Assignment editor Lacey Lecroy said she spoke with Tuff, who said she was alone with the man and his gun was visible.
"It didn't take long to know that this woman was serious," Lecroy said. "Shots were one of the last things I heard. I was so worried for her."
Complicating the rescue, bomb-sniffing dogs alerted officers to something in the trunk of a car in the school parking lot. They thought the suspect may have brought explosives, though the car turned out not to be his and had no explosives. Authorities said Wednesday that the dogs smelled a legal product that can be used to make explosives.
Students at the school arrived Wednesday morning at nearby McNair High School, where they would attend classes for the time being. The high school's marquee said "Welcome McNair Elementary School Our Prayers Are With You." The academy is named after McNair, an astronaut who died when the space shuttle Challenger exploded on Jan. 28, 1986, according to the school's website.
Associated Press writers Christina A. Cassidy, Phillip Lucas and Johnny Clark in Atlanta contributed to this report.