Sterling's family met with representatives of the Department of Justice inside the Federal Courthouse prior to the announcement.
Justice Department spokeswoman Sarah Isgur Flores told CNN the department has not communicated to anyone a decision.
Everett Matthews of Baton Rouge, holds up a sign outside the Triple S Food Mart, where Alton Sterling was killed previous year, in Baton Rouge, La., Tuesday, May 2, 2017.
Sterling was shot to death July 5, 2016 in a scuffle with two officers, Blane Salamoni and Howie Lake, outside a convenience store where he had been selling CDs.
During a 10-month probe, Federal Bureau of Investigation agents and prosecutors reviewed images of the incident captured by body cameras, cellphones and store surveillance cameras as well as witness accounts and other evidence.
Area residents, many of whom are family members of Sterling or knew him personally, are understandably devastated by the Justice Department's decision. The video was circulated widely through social media, leading some to view the shooting as proof of inherent racism in the local police force.
Chris Stewart, an attorney for the family of Alton Sterling said that while they were not pleased with the outcome, they believe that the state has a "phenomenal" case.
Amundson did not mention the alleged threat and did not take questions.
In statements, the officers said that Sterling was attempting to pull a loaded gun out of his pocket when Salamoni opened fire, according to the justice department summary.
But even before a decision is announced, the family was livid after reports surfaced Tuesday that the Justice Department has decided not to prosecute the two officers.
"The high burden meant federal prosecutors would have not only had to prove the use of force was "objectively unreasonable" but also ". that the officers acted in a willful manner with specific intent to deprive this individual of their constitutional rights", he said.
"And I have assigned a prosecutor from the Louisiana Department of Justice to assist".
Cameron Sterling, 15, said that he forgives the officer who killed his father, but he is hopeful that state prosecutors bring charges. They portrayed Salamoni as an officer who dramatically escalated the situation within seconds of encountering Sterling.
"He says the governor's office was ". assured that both our office and the Sterling family would be given advance notice of the decision". But he said that was not enough to bring charges against the officers.
Salamoni's attorney, John McLindon, said he expects the state will come to the same conclusion as the federal probe. One example of a possible state criminal charge is manslaughter. Edwards was not expected to be involved much in whether state charges would be brought against the officers - and doesn't appear to think the state police should take charge in any investigation that is launched.
The shooting of Alton Sterling, 37, was one of a series of high-profile killings of black men by white officers in recent years that sparked nationwide protests and gave rise to the Black Lives Matter movement.
Officer Michael Slager shot Scott five times in the back as the unarmed 50-year-old man ran away during a traffic stop, and cellphone video of the 2015 shooting was viewed millions of times around the world. That agency will be asked to determine whether the officers involved should face any state criminal charges.
In a press release, Landry said his office would obtain the investigative materials collected by the Department of Justice. Salamoni first fired at Sterling after he allegedly saw him reaching for the weapon, the Justice Department said.
Edwards said the leaked information also jeopardized carefully-devised public safety plans prepared for the announcement.
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