In an exclusive interview with CNN, Hawks CEO Steve Koonin said the comment during a June conference call about free agents prompted an internal investigation.
That comment was made by Hawks general manager Danny Ferry, Koonin said.
Koonin told CNN that Ferry has been punished "in excess" for the comment, but gave no details.
CNN spoke with a source with knowledge of the Hawks probe who said that Ferry was relaying information that an outside party had given him about player Luol Deng. Deng now plays for the Miami Heat.
Hawks owners were on the call, the source told CNN. It's common for a team, when discussing free agent players, to gather information about those players, because they could be given multimillion-dollar contracts.
What Ferry relayed was racially insensitive, and that prompted one of the team's owners to say that a closer look at the organization was needed. An investigation began. During that probe, Levenson's email was uncovered.
Attempts to reach Ferry on Monday were unsuccessful.
On Sunday, Ferry told the Atlanta Journal-Constitution
: "I support Steve (Koonin)'s leadership and greatly appreciate his support. I look to learn from this situation and help us become a better organization."
A two-month investigation
After the June conference call, the Hawks brought in an outside law firm to review the organization from top to bottom, in an investigation that took two months to complete.
"There were 19 people interviewed, 24,000 pieces of evidence looked at, and in that discovery -- that internal investigation -- this email that we released this morning was found, from Bruce Levenson," Koonin told CNN's Martin Savidge on Sunday night.
"Bruce was confronted with this email from 2012, and he decided that instead of fighting it ... he thought it was best for the city, for the team, for his family, to walk away."
The email to Ferry -- which bemoaned the high percentage of black cheerleaders and said that white fans may have been scared away by black fans -- led Levenson to announce Sunday that he will sell his controlling stake in the team.
Levenson's 2012 email addressed the troubles the franchise faced in attracting more affluent white season-ticket holders. The owner said he had taken a look around Philips Arena and noticed a few things.
First, the audience was 70% black, he wrote. The stadium's bars were 90% black. The cheerleaders were black. There were few fathers and sons at the games. The music played in the arena was hip-hop, and the after-game concerts were either rap or gospel acts.
"Then i start looking around at other arenas. It is completely different. Even (Washington) DC with its affluent black community never has more than 15 pct black audience," he wrote.
Koonin has been the Hawks' CEO for two months. He said he was "mortified and angry" about the email and met with the team's players Sunday night.
"It was like walking into a funeral," Koonin said of the meeting.
"These are young men who wear our city's name and our logo on their chest. They play for a team, and they are supposed to be supported by their ownership. And ownership failed in supporting them."
'I trivialized our fans'
In his announcement Sunday, Levenson said he will sell his controlling stake in the team after an "email two years ago that was inappropriate and offensive."
A man answering the phone at his Maryland home told CNN that Levenson was not taking any phone calls.
In focusing on low attendance at Hawks games and the need to boost season-ticket sales and corporate sponsors, Levenson said in his statement, he had spoken with executives about diversifying the fan base and including more suburban whites. During those discussions, "I shared my thoughts on why our efforts to bridge Atlanta's racial sports divide seemed to be failing," he wrote.
"I trivialized our fans by making cliched assumptions about their interests (i.e. hip hop vs. country, white vs. black cheerleaders, etc.) and by stereotyping their perceptions of one another (i.e. that white fans might be afraid of our black fans)," he said in his statement. "By focusing on race, I also sent the unintentional and hurtful message that our white fans are more valuable than our black fans."
'The black crowd scared away the whites'
In his 2012 email, Levenson wrote that before his Atlanta Spirit Group bought the Hawks in 2003, thousands of tickets were being given away, mostly to the black community, in an effort to make the arena appear less empty.
It was a trend that continued for a couple of years after the Atlanta Spirit Group took over, he wrote in a seemingly informal email rife with punctuation errors and misspellings.
"My theory is that the black crowd scared away the whites and there are simply not enough affluent black fans to build a signficant season ticket base," he wrote. "i never felt uncomfortable, but i think southern whites simply were not comfortable being in an arena or at a bar where they were in the minority."
Levenson derided claims on fan websites that the arena is unsafe or in a bad part of town as "racist garbage," but then suggested an array of changes inside the stadium, all based on race.
'I want some white cheerleaders'
"I have been open with our executive team about these concerns. I have told them I want some white cheerleaders and while i don't care what the color of the artist is, i want the music to be music familiar to a 40 year old white guy if that's our season tixs demo," he wrote.
He continued, "i have also balked when every fan picked out of crowd to shoot shots in some time out contest is black. I have even bitched that the kiss cam is too black."
Things had changed since Levenson implemented these suggestions, he wrote, boasting that the crowd was closer to 40% black by 2012, by his admittedly unscientific estimate. That was still four to five times higher than other NBA franchises, he wrote, "and my further guess is that 40 pct still feels like 70 (percent) to some whites at our games. Our bars are still overwhelmingly black."
While noting this was a sensitive issue, Levenson went on to declare it "far and way the number one reason our season ticket base is so low. And many of our black fans don't have the spendable income which explains why our (food and beverage) and merchandise sales are so low. At all white thrasher games sales were nearly triple what they are at hawks games."
The year before Levenson wrote the controversial email, the Atlanta Spirit Group sold its NHL team, the Atlanta Thrashers, to a Canadian ownership group that moved the team north of the border. It's now called the Winnipeg Jets.
Comparisons to Donald Sterling
In his Sunday statement, Levenson said the NBA should have no tolerance for racism, a sentiment he also expressed during a CNN interview earlier this year when he talked about Donald Sterling, the Los Angeles Clippers owner who was caught making racist remarks on tape.
Discussing Sterling's reluctance to sell the team after the scandal broke, Levenson said in May that, as a fellow team owner, he couldn't be partners with someone who holds those types of views.
"I think I speak for all of my partners when I say we were all deeply offended. We all quickly spoke out against the words we heard on that tape," Levenson said.
NBA Commissioner Adam Silver, who brought the hammer down on Sterling, called Levenson's 2012 email "entirely unacceptable" and commended Levenson for self-reporting to the league office.
Levenson told the league in July about the August 2012 email, and the NBA conducted an investigation, the statement said.
"(Levenson) shared with me how truly remorseful he is for using those hurtful words and how apologetic he is to the entire NBA family -- fans, players, team employees, business partners and fellow team owners -- for having diverted attention away from our game," Silver said.
The league will work with the Hawks to determine the appropriate sale process for the team, Silver said. Koonin, the Hawks CEO, will oversee team operations, the league said.
In closing his statement, Levenson said he was embarrassed by the email and apologized to the team and its fans.
"To the Hawks family and its fans, you have my deepest gratitude for the past ten years," Levenson wrote. "Working with this team and its extraordinary executives, coaching staff, and players has been one of the highlights of my life. I am proud of our diverse, passionate, and growing legion of Hawks fans, and I will continue to join you in cheering for the best team in the NBA."
According to the Hawks website, Levenson, a former journalist, co-founded United Communications Group, a portfolio of business information companies, and is a founding shareholder and former board member for TechTarget, a technology media company.
Koonin said that while Levenson will make money from the sale, he is still paying a price.
"The only thing we all have in our life is our reputation, and his was damaged today -- by him, and not by anyone else."