SAN FRANCISCO (CBS SF) — Four members of a Northern California militia group associated with the “boogaloo” far-right, extremist movement have pleaded guilty to obstructing the investigation into the May 2020 shooting at the Oakland federal building that killed a security officer and injured a second officer, federal authorities said Monday.

In addition, one of the four militia members pleaded guilty to enticing a 15-year-old girl to produce and send him child pornography, according to a statement from Acting U.S. Attorney for the Northern District of Califonia Stephanie Hinds and FBI Special Agent in Charge Craig Fair.

Jessie Rush, 29, of Turlock; Robert Blancas, 33, a transient resident of the Bay Area; Simon Ybarra, 23, of Los Gatos; and Kenny Miksch, 21, of San Lorenzo, were indicted on March 23 in connection with their plot to destroy destroying communications and other records related to the shooting death of Federal Protective Service officer David Patrick Underwood and the wounding of his partner at the Ronald V. Dellums Federal Building.

On Monday, Miksch pleaded guilty to the charges in United States District Court, the last of the four defendants to do so, according to the statement.

In their guilty pleas, the men admitted they joined an armed anti-government militia group named the “1st Detachment, 1st California Grizzly Scouts” in April 2020 after having connected Facebook group that catered to the “boogaloo” movement. The term “boogaloo” refers to what extremists believe is a politically motivated civil war or uprising against the government.

The four admitted meeting for training operations in firearms and combat, in sessions that labeled law enforcement as potential “enemy forces” and suggested using lethal force and taking prisoners. All four acknowledged in their plea agreements that they engaged in June 2020 discussions with other Grizzly Scouts about “boog” (boogaloo), waging war against the government, and tactics for killing law enforcement personnel, including police officers, the statement said.

The suspected gunman in the Oakland federal building shooting, former Air Force sergeant Steven Carillo, was also a member of the Grizzly Scouts, according to court documents. Carillo has also been charged with the murder of Santa Cruz County Sheriff’s Sgt. Damon Gutzwiller and attempted murder of other deputies in an ambush in June 2020 in the mountain community of Ben Lomond.

Rush, Blancas, Ybarra, and Miksch each acknowledged in their plea agreements that they learned a Grizzly Scouts member was allegedly involved in the Oakland federal building shooting and admitted that the Grizzly Scouts member communicated on WhatsApp militia group chat about his alleged attack on the Santa Cruz County deputies in Ben Lomond

According to their plea agreements, that member asked the other group members to come to his aid and said, “Dudes i offed a fed.” Rush admitted he instructed that member to delete data on his phone and get out of there. Rush, Blancas, Ybarra, and Miksch each admitted to conspiring with other group members to destroy the records of their interactions and communications because they foresaw authorities would investigate and prosecute that Grizzly Scouts member.

The four also admitted destroying records and communications from the WhatsApp group, and Blancas admitted to destroying cloud-based files on the Grizzly Scouts rank structure, confidential documents, liability waivers, and a scorecard assessing the skills of Grizzly Scouts members in combat, firearms, medical, and other training.

Separately, Blancas pleaded guilty to enticing a minor to engage to produce child pornography, admitting that from about April through September 2020, he enticed a 15-year old girl to repeatedly make and send him dozens of pornographic photos and videos of herself. Blancas admitted that he knew she was a minor when he did so.

Blancas pleaded guilty on August 23 to the enticing and the conspiracy to obstruct justice charges and is scheduled to be sentenced on December 6. Rush and Ybarra pleaded guilty on September 13 and Miksch pleaded guilty on September 20 to one count of conspiracy to obstruct justice. Rush is scheduled to be sentenced on January 10, while Ybarra and Miksch are scheduled to be sentenced on February 7.