SAN FRANCISCO — A follower of the anti-government Boogaloo movement has been convicted of murder and attempted murder in the May 2020 drive-by shooting that targeted court security officers outside Oakland’s federal building, authorities said.

Robert Alvin Justus Jr., 33, of Milbrae, was found guilty by a jury that deliberated for several hours over a two-day period. He now faces a mandatory life sentence.

Justus was the driver of a modified white van owned by fellow Boogaloo follower Steven Carrillo, who was the impetus behind the murder plot. The two met up at a BART station in San Leandro, immediately drove to Oakland and gunned down Federal Protective Service Officer Dave Patrick Underwood outside the Ronald V. Dellums Federal Building in downtown Oakland. A second FPS officer was wounded by the gunfire.

According to the FBI, the two were influenced by the so-called Boogaloo movement, a loosely organized anti-government group that believes a second Civil War is looming. During trial and an FBI interrogation, Justus attempted to portray himself as an unwilling participant, telling agents that Carrillo essentially forced him into the murder plot at gunpoint and that he expected to simply attend a protest over George Floyd’s murder that was held in Oakland the same night.

Justus came forward to the FBI, but only after Carrillo ambushed Santa Cruz and California Highway Patrol officers near his home in Ben Lomond, killing Sheriff’s Sgt. Damon Gutzwiller and wounding three other law enforcement officers. Carrillo entered guilty pleas to both shootings and was sentenced to life in state court and 40 years in federal court.

In his FBI interrogation, Justus admitted to driving past the federal building while Carrillo opened the sliding door of the van and opened fire at the security booth, killing Underwood and wounding his partner. But he insisted that Carrillo had him at gunpoint during parts of the drive, and that he’d actually talked Carrillo out of killing a bus driver and attempting to shoot down a police helicopter before the shooting.

Prosecutors argued that surveillance video around the federal building showed Justus get out of the van and do reconnaissance of the area, before reporting back to Carrillo. They also argued that his returning to Carrillo’s van when he had an opportunity to flee was evidence of his willingness to join the plot.

Justus testified in his own defense during trial. So did Underwood’s partner, who watched in disbelief as their security booth was riddled with bullets.

“I just felt getting hit, and getting knocked down,” Sombat Mifkovic recalled from the witness stand.“I called out to my partner and he was not responsive.”

The bullet-riddled windows remained installed in the booth for months, serving as a grisly reminder of the crime to Underwood’s colleagues and passers-by, until court staff finally replaced them.

Staff writer Jakob Rodgers contributed to this report.