"[Phillips] just appeared and it was too late," he said Sunday. "It was instantaneous. No suffering."
Police said alcohol was not a factor for either driver in the accident. Neither Phillips nor Chapman were wearing seat belts, according to Pierce. Stewart and the driver of the third car had their seat belts fastened, said Pierce.
Joseph Chapman said the family hasn't yet seen their son's fiancee — a first-grade teacher at Timber Ridge Elementary — since the accident, but they're in close communication.
Jay Chapman was the second child of three sons, and an avid athlete, his father said. He lettered in baseball and basketball at Fayette County High, and in college he was twice named intramural athlete of the year. At South Cobb, he served as an assistant baseball, basketball and softball coach. Ultimately, his father said, he wanted to coach golf, too.
"He was very loving, very loyal and extremely sweet," his father said, sharing an anecdote about a young Jay's medical visit when he was 5. When his doctor told Jay he could have one treat for good behavior, Jay asked for three.
"'I want one each for my brothers,'" Joseph Chapman tearfully recalled his son saying.
South Cobb principal Grant Rivera said Jay Chapman made a huge impact in his three years at the school by dedicating himself to students year-round.
"He was very selfless with his time," Rivera said. "He'd come in early to help kids prepare for exams or study, and during the summer you'd frequently find him up at school working with kids in sports. He touched a lot of lives."
Chapman taught seniors primarily. Before Saturday's graduation ceremony, counselors were on hand "because obviously there were a lot of kids impacted," Rivera said.
Counselors also will be available this week to help faculty cope with the loss of "an exceptional colleague and an exceptional friend to so many," Rivera said.
South Cobb will find a way to honor Chapman, Rivera added.
"We're going to be working with the family, when the time comes, to see what they'd like to do to best memorialize him," Rivera said.
Chapman's family is pulling together to plan his funeral services, though they are unsure when his body will be able to come home. According to Louisiana law, Joseph Chapman said, Jay Chapman's body must be autopsied and embalmed before it is released.
Joseph Chapman said his family plans to fly to New Orleans to accompany his son's return.