College Park (US), Jan 1 (AP) Maryland prosecutors have ruled out criminal charges against any police officers in the shooting death of a man whose family says he was sleeping in his bed next to his girlfriend when police opened fire, an attorney for the family has said.

Howard County State's Attorney Rich Gibson Jr. informed the parents and girlfriend of 21-year-old Duncan Socrates Lemp of the decision during a meeting conducted remotely, family attorney Rene Sandler told The Associated Press on Thursday.

Gibson's office concluded that police in neighboring Montgomery County were justified in using deadly force against Lemp, Sandler said. Members of a tactical unit were serving a "no-knock" search warrant at the Lemp family's home about 4:30 a.m. on March 12 when an officer fatally shot him.

A spokeswoman for Gibson's office didn't immediately respond to a phone call and text message seeking comment on the decision.

Lemp's shooting galvanized a loose network of gun-toting, anti-government extremists promoting the "boogaloo," a slang term for a second civil war or collapse of civilization.

Many "boogaloo" movement promoters have hailed Lemp as a martyr and turned his name into a hashtag campaign on social media.

Lemp's girlfriend and parents say the software engineer was asleep in his bedroom when police fired at him from outside the house in Potomac, Maryland, a suburb of Washington, D.C., according to Sandler.

The family's account contradicts a statement issued by Montgomery County police. The department has said Lemp was armed with a rifle and ignored commands to show his hands and get on the floor when officers entered his family's home.

The nascent "boogaloo" movement has been linked to a string of domestic terrorism plots and has been promoted by white supremacists, but many supporters insist they're not truly advocating for violence.

A post on Lemp's Instagram account shortly before his death depicted two people holding up rifles and included the term "boogaloo," which derives from the name of a 1980s-era movie sequel. (AP)

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