Air force sergeant linked to ‘boogaloo’ movement charged in federal officer’s death

An air force sergeant already jailed over the ambush killing of a California sheriff’s deputy was charged in connection with the shooting death of a federal security officer outside the US courthouse in Oakland during a night violent protest last month. Officials say the man has ties to the anti-government “boogaloo” movement.

SSgt Steven Carrillo, 32, was charged on Tuesday with murder and attempted murder in the killing of 53-year-old federal officer Dave Patrick Underwood.

Carrillo separately faces state charges in the 6 June ambush and fatal shooting of Santa Cruz county sheriff’s Sgt Damon Gutzwiller and the wounding of four other officers in Ben Lomond, an unincorporated area outside the beachfront city of Santa Cruz, south of San Francisco.

Related: Deadly shooting outside Oakland courthouse as protests rage

Carrillo, a leader of an elite military security force, had multiple links to the far-right, anti-government “boogaloo” movement, federal prosecutors said at a news conference on Tuesday.

Law enforcement officials said they identified multiple pieces of evidence that linked Carrillo to the developing anti-government extremist movement associated with the term “boogaloo”, an ironic word for “a violent uprising or impending civil war in the United States”.

Law enforcement officials discovered a ballistic vest with a “boogaloo” flag on it in a van they said Carrillo had used, and also alleged that Carrillo had written phrases associated with the movement in his own blood on the hood of a car he hijacked, according the criminal complaint against Carrillo.

The phases in blood included “boog,” short for “boogaloo”, and “I became unreasonable”, a phrase associated with Marvin Heemeyer, an anti-government extremist from Colorado who is frequently cited in “boogaloo” social media groups, NBC News reported.

Underwood died from gunshot wounds in a drive-by shooting outside the Ronald V Dellums Federal Building in Oakland on 29 May. Another federal officer was critically injured. The two contract security officers worked for homeland security’s Federal Protective Service and had been monitoring a nearby protest over the death of George Floyd.

Authorities say Carrillo used an AR-15-style weapon in the shooting. A second man described as the driver of the car was charged with aiding and abetting the murder and attempted murder.

Although the concept of “the boogaloo” is popular with white supremacist accelerationists, it has also attracted a broader spectrum of American anti-government extremists.

The imagery in the “boogaloo” flag patch – an Igloo and a line of Hawaiian print – reference alternative terms for “boogaloo” that have spread in social media discussions, including “big igloo” and “big luau.”

“Boogaloo” rhetoric often identifies law enforcement officials, especially federal officials, as the enemy. Men carrying guns and wearing Hawaiian-print shirts, a symbol of the “boogaloo”, have showed up at protests over the killing of George Floyd by police across the country, including in Minneapolis, Salt Lake City, Dallas, Atlanta, and Philadelphia, the Washington Post reported.

The term “boogaloo” has also spread among a wide spectrum of pro-gun activists, including in the lead-up to a massive protest this January against new gun control laws in Virginia.

“The ‘boogaloo’ movement is not a defined group,” an FBI agent noted in the affidavit supporting the criminal complaint against Carrillo. “In general, followers of the ‘boogaloo’ ideology may identify as militia and share a narrative of inciting a violent uprising against perceived government tyranny.”

Facebook has been “the main organizational point” for “boogaloo” groups, according to Alex Friedfeld, a researcher with the Anti-Defamation League’s Center on Extremism, which has been monitoring the spread of “boogaloo” rhetoric online.

Facebook announced on 4 June it would be taking some steps to make it more difficult for users to find groups associated with the term “boogaloo”, Reuters reported, but the social network is again facing criticism for not doing enough to crack down on far-right organizing on its platform, even as the death toll associated with the movement continues to climb.

Carrillo is being held without bail in jail in Monterey county and is expected to enter a plea to the state charges on Wednesday.