By June 2, 2020, investigators believed the attackers were targeting uniformed officers. An abandoned white van that held firearms, ammunition, and bomb-making equipment contained evidence that led to Carrillo's home in Ben Lomond. A ballistic vest found in the white van bore a patch with the boogaloo symbols of Hawaiian-style print and igloos. According to an official from the
Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF), a homemade machine gun with a silencer was used in the shootings. The weapon was a
homemade firearm and did not have manufacturer markings. Acting
Deputy Secretary of Homeland Security Ken Cuccinelli described the Oakland shooting as an "act of
domestic terrorism". The FBI announced on June 16 that Steven Carrillo was associated with the
boogaloo movement and that he and Justus had deliberately chosen the night of
protests in Oakland for cover for the May 29 attack. The FBI agent-in-charge of the investigation stated, "There is no evidence that these men had any intention to join the demonstration in Oakland. They came to Oakland to kill cops." Beforehand, Carrillo posted on Facebook, "Go to the riots and support our own cause. Show them the real targets" and "Use their anger to fuel our fire. Think outside the box. We have mobs of angry people to use to our advantage." The attack took place several blocks from a protest at
Oakland City Hall. A former friend of Carrillo's told interviewers, "Excessive use of force on unarmed civilians — that was a huge thing for him... It was a mental tipping point for him." The hijacked car had "boog", "I became unreasonable", and "stop the duopoly" written in Carrillo's blood on the vehicle's hood. "Stop the duopoly" is also a popular fixation among boogaloo adherents, referring to the dominance of the
Republican and
Democratic parties in American politics. The FBI agent in charge of the investigation said in a news conference that the suspects did not appear to intend to join the protests, saying, "They came to Oakland to kill cops." Using a search warrant, the FBI investigated posts from Carrillo's Facebook account posted between May 28 and 29. One message read, "It's on our coast now, this needs to be nationwide. It's a great opportunity to target the specialty soup bois." (According to the FBI, "soup bois" may refer to federal law enforcement agents.) Another read, "Its kicking off now and if its not kicking off in your hood then start it. Show them the targets." Justus was declared a suspect in the Oakland shooting and placed under FBI surveillance. He turned himself in at the federal building in San Francisco five days after Carrillo's arrest. ==Prosecution==