Four police officers have been arrested and charged with federal crimes over the death of Breonna Taylor, an innocent 26-year-old black woman killed in a botched "no-knock" raid on her home in Louisville, Kentucky.

Federal prosecutors accused the officers of several crimes, including lying to obtain the warrant that was used to search Taylor's home and then staging a cover-up in relation to the case that set off nationwide protests over racial injustice and policing.

Attorney-General Merrick Garland said the four current and former Louisville Metro Police Department officers were being charged with civil rights offences, unlawful conspiracy, unconstitutional use of force and obstruction.

The Department of Justice (DOJ) had charged former Detective Joshua Jaynes, Detective Kelly Goodlett, former Detective Brett Hankinson, and Sgt. Kyle Meany with civil rights violations and unconstitutional use of force.

"The federal charges announced today allege that members of a Police Investigations Unit falsified the affidavit used to obtain the search warrant of Taylor's home and that this act violated federal civil rights laws, and that those violations resulted in Taylor's death," Garland said in a press conference on Thursday.

Breonna Taylor, an emergency medical technician (EMT) worker, and her boyfriend were asleep when police burst in and shot her eight times. Photo / Courtesy of Family of Breonna Taylor

The DOJ alleges that Jaynes lied on the search warrant application that let officers raid Taylor's home. He wrote in the search warrant that he "verified with a U.S. Postal Inspector" that Taylor's ex, whom police suspected of dealing drugs, had been receiving mail at her address. However, an internal investigation found that Jaynes had not verified the information with a postal worker himself, but rather relied on another officer's false word.

"Among other things, the affidavit falsely claimed that officers had verified that the target of the alleged drug trafficking operation had received packages at Taylor's address. In fact, defendants Jaynes and Goodlett knew that was not true," Garland told reporters.

Garland also alleged that Jaynes and Goodlett knew armed officers would be carrying out the raid at Taylor's home, and that conducting the search could create "a dangerous situation for anyone who happened to be in Taylor's home."

Prosecutors allege that Jaynes and Goodlett met in a garage after Taylor's death "where they agreed to tell investigators" looking into the botched raid "a false story."

The killings of Taylor and George Floyd, who was murdered by a white police officer in Minneapolis in May 2020, became the focus of a wave of mass protests in the US and beyond against racial injustice and police brutality.

Violent protests erupted across the nation following the results of a grand jury investigation into the police shooting death of Breonna Taylor including in Portland. Photo / Getty Images

Tensions were further inflamed when no one was charged in relation to Taylor's fatal shooting.

Taylor was killed when Louisville officers conducted a raid of her apartment on March 13, 2020, at around 12:45am. When officers broke down the door to the apartment, Taylor's boyfriend thought it was an intruder and fired a single gunshot using a legally purchased firearm, hitting the first officer at the door, and they returned fire, striking Taylor six times. Officers fired 32 rounds in total.

Two Louisville officers fired a total of 22 shots into the apartment, one of which hit Taylor in the chest, according to information filed by the Justice Department. A third officer moved from the doorway to the side of the apartment and fired ten more shots through a window and a sliding-glass door, both of which were covered with blinds and curtains.

Garland said he spoke with Taylor's family earlier Thursday and informed them of the charges.

"We share, but we cannot fully imagine, the grief felt by Breonna Taylor's loved ones and all of those affected by the events of March 13, 2020. Breonna Taylor should be alive today," he added.

Civil rights lawyer Ben Crump, who represented Taylor's family through a historic $12 million settlement, said the latest developments in the case marked "a great day".

In a statement with other lawyers who represented the family, he described it as a "huge step toward justice."

- Megan Palin, news.com.au