Karen Wells, Amir Locke's mother, vowed to continue to fight after Minnesota authorities announced no charges would be filed in the shooting death of her son by police executing a "no-knock" search warrant.
Locke was shot dead in February by Minneapolis police who were searching for a suspect in a murder investigation.
Ms Wells said the officer who shot Locke, Mark Hanneman, is "guilty" after prosecutors announced he would not be charged.
"This is not over. You may have been found not guilty, but in the eyes of me, being the mother who I am, you are guilty," Ms Wells said.
"I am not disappointed. I am disgusted with the city of Minneapolis," she said.
A video shows members of a police SWAT team entering the apartment shortly before 7am while shouting "Police, search warrant!"
Then Locke, who was sleeping on a couch, starts to rise from beneath a blanket with a gun in his hand when police open fire.
Police entered the apartment using a controversial "no-knock" warrant. Locke was not a suspect in the murder case and was authorised to own a firearm.
Minnesota Attorney General Keith Ellison on Wednesday said the authorities were declining to file any criminal charges against the officers involved.
"Amir Locke is a victim," Mr Ellison said in a statement. "He should be alive today, and his death is a tragedy."
But the attorney general said police officers have the right to use deadly force to protect their life or the life of someone else. Body camera footage showed that Locke had pointed a gun at Mr Hanneman, prosecutors said.
"Under current law — and as awful as the circumstances of this tragedy are — there is not sufficient admissible evidence to support a criminal charge," Mr Ellison said.
The state attorney general said the case raises questions about whether the police should continue to use these controversial warrants, which have been banned in some jurisdictions.
"No-knock warrants are highly risky and pose significant dangers to both law enforcement and the public, including to individuals who are not involved in any criminal activity," he said.
Locke's death reopened wounds in Minneapolis that were caused by the May 2020 murder of George Floyd, a 46-year-old black man, by a white police officer.
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Protesters march on the Brooklyn Bridge during a demonstration on the first anniversary of the death of George Floyd, in New York. Reuters -
Some streets in Manhattan were closed due to the demonstrations on Tuesday evening. AP -
The musician Common performs with the Sounds of Blackness at George Floyd Square in Minneapolis, Minnesota. Floyd's death in May 2020 led to worldwide protests and calls for police reform or abolition. Getty -
Robin Puttin leads a prayer while kneeling and raising her hand on the first anniversary of George Floyd's death, at George Floyd Square, in Minneapolis, Minnesota. Reuters -
Electric and LED candles bearing the names of people killed by police illuminate the fist sculpture as people gather at the George Floyd Square. Reuters -
A man is reflected in a sign during a vigil held to remember George Floyd in Lynn, Massachusetts. Reuters -
House Speaker Nancy Pelosi meets the family of the late George Floyd at the US Capitol in Washington. The family met President Joe Biden and various US politicians, and participated in a memorial at Black Lives Matter Plaza. EPA -
People gather at the sight where George Floyd was killed one year ago, at 38th Street and Chicago Avenue in Minneapolis - an area now called George Floyd Square. EPA -
A man stands next to a mural of George Floyd in Houston, Texas. Reuters -
A family member holds onto Gianna Floyd, daughter of George Floyd, at the White House following their meeting with President Biden in Washington. Reuters -
Gianna Floyd and other family members and lawyers, raise fists after meeting President Biden in Washington. Reuters -
Community organiser Tommy McBrayer leads a chant in solidarity with George Floyd, at George Floyd Square, in Minneapolis. Reuters -
New York City Mayor Bill de Blasio and Reverend Al Sharpton kneel with community leaders for nine minutes and 29 seconds, symbolising Floyd's ordeal at the hands of police. Reuters -
Philonise Floyd, brother to George Floyd, puts his arm around Speaker Nancy Pelosi, near Rep. Karen Bass, as he and other members of the Floyd family meet politicians at the US Capitol. Reuters -
A man places a candle at a memorial in honour of George Floyd, at George Floyd Square in Minneapolis. Reuters -
Black Lives Matter protesters hold placards and shout slogans in Brooklyn, New York. AFP -
People gather at George Floyd Square in Minneapolis. AP -
A man sits in front of the Say Their Names cemetery, close to George Floyd Square, in Minneapolis. AP -
Two women sit on a roof as they listen to a memorial music performance, at George Floyd Square, in Minneapolis. EPA
Agencies contributed to this report
