Four men accused of the $1.3 million mineral heist at the California State Mining and Mineral Museum are scheduled to be arraigned today in Mariposa County Superior Court.
Matthew Campbell, 43, Jonathan Matis, 41, Edward Rushing III, 40, and Christopher Scott Sheffield, 42, were arrested last week during a multiagency investigation, spearheaded by the California Highway Patrol.
All four suspects are facing charges of conspiracy to commit robbery, but some have been linked to other crimes in Sacramento and Placer counties, authorities said.
The incident occurred Sept. 28, when robbers entered the museum's vault about 4 p.m. after threatening a guide and curator with pickaxes. Authorities said they were dressed in black and wearing hoods to conceal their identities.
During the two-minute robbery, the men took off with several gold pieces and gems after smashing display cases.
According to the CHP, they tried to steal one of the museum's most prized pieces, a 14-pound gold piece called the Fricot Nugget, but the alarm went off before they could break the case.
The heist was captured on the museum's surveillance cameras.
The museum, which is operated by the California Department of Parks and Recreation, is home to more than 13,000 artifacts dating to the 1800s.
The suspects remain in custody at the Mariposa County Jail.