COLLEGE PARK, Md. (AP) — Maryland prosecutors on Thursday ruled out criminal charges against a police officer who fatally shot a man during a tactical team's predawn, no-knock raid on his family's home, a killing that galvanized a loose network of anti-government extremists this year.

Duncan Socrates Lemp's family says the 21-year-old was sleeping in his bed next to his girlfriend when a Montgomery County police officer opened fire, but prosecutors concluded that Lemp pointed a rifle at the officer and posed a threat.

Howard County State's Attorney Rich Gibson Jr.’s office, which reviewed the case and presented evidence to a grand jury, said in a 17-page report that the unidentified officer was justified in using deadly force.

Members of a tactical unit were serving the no-knock search warrant at the Lemp family’s home about 4:30 a.m. on March 12 when the officer fired five shots through a shattered window from outside, hitting Lemp all five times.

Family attorney Rene Sandler said the report reveals that no body camera videos captured the shooting. She also noted that prosecutors concluded there was no evidence of any crossfire or that Lemp’s gun had been fired.

Sandler said the family, who also is represented by attorney Jon Fellner, is “extremely disappointed that prosecutors declined to charge for the murder of their son.”

“In reaching their conclusion, they had to unfortunately ignore very important facts from eyewitnesses,” she added. Sandler said the family likely will sue "everyone responsible.”

The shooting turned Lemp into a martyr for 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 turned his name into a hashtag campaign on social media.

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.

On social media accounts, Lemp’s username was “YungQuant.” On an internet forum called My Militia, a user identifying himself as Duncan Lemp, of Potomac, and posting under the username “yungquant” said he was “an active III%’r and looking for local members & recruits.” That’s an apparent reference to the Three Percenters, a wing of the militia movement.

Detectives obtained the no-knock warrant to search Lemp's home after receiving an anonymous tip that he illegally possessed firearms, police said. Lemp had a criminal record as a juvenile that made it illegal for him to legally possess or buy firearms in Maryland until he turned 30, according to police.

A “confidential source” told investigators in February that Lemp was involved in the Three Percenters and had made “anti-police” statements in the past, prosecutors said.

“The police felt that knocking and announcing their presence would put the officers in serious danger if Lemp decided to resist his arrest,” prosecutors wrote.

Less than a month before the shooting, Lemp said in a text message that he was "packing 24/7 but you know of course that has consequences.”

“I really do feel the boog though," he added. “I might not survive to see it but I’m confident my brothers will.”

Lemp's parents, Mercedes and Matt Lemp, told The Associated Press in October that their son wasn’t a threat to the tactical unit officers who stormed their house. They also don’t believe he was part of any extremist movement.

Lemp’s girlfriend, Kasey Robinson, and his parents have said 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.

Prosecutors said the evidence doesn't support Robinson's contention that bullets shattered the bedroom window. They believe that it was more likely that Robinson heard another SWAT team member manually break the window before the officer fired.

“Anyone put through that kind of sensory overload would have difficulty recalling exactly what happened. It’s an extremely chaotic situation” the report says.

The officer who fatally shot Lemp was placed on administrative leave, a standard procedure.

The officer, who isn't named in the report, told investigators that he repeatedly shouted, “Police, show me your hands!” and saw a screaming Robinson hold up her hands before he saw Lemp get out of bed. The officer said Lemp ignored his commands to show his hands, bent down and picked up a rifle. He believes he repeatedly said, “Don’t do it,” as Lemp raised the rifle and pointed it at him.

“At this point, the (officer) thought that Lemp was going to kill him and so he made the decision to shoot Lemp,” the report says.

No other officer could see what the officer saw when looking through the window but at least six officers heard him yelling commands, according to prosecutors.

Lemp's bedroom also had an exterior door where authorities found a “booby trap” affixed to the frame, designed to fire a shotgun shell at anyone entering the room from outside the home, according to police.

Police detectives recovered three rifles and two handguns from the home.

Robinson’s attorney, Cary Hansel, believes Howard County prosecutors “cherry-picked” secret grand jury testimony to cite in their report. Hansel called on the state’s attorney to publicly release all of the testimony and evidence they presented to the grand jury.

“The two issues are: What charges if any were presented to the grand jury, and then what decision if any did the grand jury make?” he asked.