“I want to acknowledge and thank my friend, Will Packer, who is doing a documentary on the missing and murdered children,” Bottoms said. The program airs at 9 p.m. Saturday.

Bottoms recalled living through the terrifying chapter in Atlanta’s history as a 9-year-old. The new look at evidence, she said, is meant to assure the families that “we have done all that we can do to make sure their memories are not forgotten and, in the truest sense of the word, to let the world know that black lives do matter.”

The operation will be a joint one, with authorities from the Atlanta Police Department, the Fulton County District Attorney’s Office and the Georgia Bureau of Investigation using modern technology to test stored evidence such as DNA or cloth or carpet fibers. Fulton County District Attorney Paul Howard said this will be the first project of his office’s soon-to-be formed Conviction Integrity Unit.

Williams, who has maintained his innocence, is held at Telfair State Prison in southeast Georgia. After his 1982 conviction for the murders of two young adults in Fulton County, where the vast majority of deaths occurred, authorities there announced they were convinced Williams was also guilty in the child murders and closed the cases.

Ronald Kuby, one of his former attorneys, called the renewed investigation an “overdue” step that could answer lingering questions. Williams couldn’t immediately be reached for comment.

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In DeKalb County, where five cases from the Atlanta Child Murders period remain open, the police department said it would cooperate with Atlanta’s efforts. Officials have disagreed over the years whether the DeKalb cases should be attributed to Williams.

Some victims’ relatives also have questioned whether officials rushed to judgment decades ago by suggesting Williams was guilty of all the murders.

Leach-Bell, whose son’s case is among the five in DeKalb, praised the mayor and other Atlanta officials for deciding to check the evidence again.

“I am so happy to hear what I heard today,” Leach-Bell said during the news conference. “It’s brought a little comfort in my heart. I have been let down for many, many, many, many, many, many, many years.”

One letdown came in 2005 after a fruitless effort by DeKalb police to re-investigate its cases. Then Police Chief Louis Graham reopened the cases and championed the idea that Williams hadn’t committed the murders. That investigation stalled a year later when Graham resigned amid an unrelated controversy.

Three of the DeKalb cases were among 10 so-called “pattern cases” that Fulton prosecutors discussed at Williams’ trial to make their case that he was the lone killer who terrorized the city. (Leach-Bell’s son’s death wasn’t considered a pattern case.)

Whether the new review of evidence produces results or not, the mayor said she is also working on another of the families’ priorities: honoring the victims. Bottoms created a task force to explore how best to do that. The mayor took a step Thursday by reading victims’ names aloud during the news conference.

Atlanta Police Chief Erika Shields said she hoped the fresh look at the cases would help the city make the dark period from 1979 to 1981 when the children, nearly all boys, were killed more than a “footnote” in Atlanta’s story. She said officials also have an “obligation” to make sure they’ve tried everything possible to bring closure.

Retired Atlanta homicide detective Danny Agan, who appears in the Investigation Discovery documentary, said he believes Williams committed most of the murders, but not necessarily all of them. Agan, who stood behind the mayor during her announcement, said he didn’t view the planned new testing as a jab at the original police work. He said the spirit of the mayor’s inquiry was the correct one: to find the truth.

“The truth won’t hurt you,” he said.