Three Santa Rosa men accused of plotting to steal an armored car carrying millions of dollars now face federal charges of conspiring in the heist.

Monico Dominguez, 39; his brother Juan Dominguez Jr., 26; and Shawn Geernaert, 33, were taken into federal custody and on Monday were charged in U.S. District Court in San Francisco.

The men already were accused in Sonoma County Superior Court of conspiring to rob a Garda Cash Logistics car in Santa Rosa on Aug. 6, a plan they abandoned the night of the robbery attempt.

But a federal indictment filed Thursday potentially brings harsher penalties.

Juan Dominguez and Geernaert pleaded not guilty Monday, according to court documents. Geernaert, also accused of cultivating marijuana at his Dutton Meadow cabinet shop, was released on $50,000 bail.

Federal prosecutors also accused Monico Dominguez of carrying out a $1 million robbery one year before at the Garda facility. Police said Dominguez was among the armed men who stormed the Northpoint Parkway facility.

After the 2011 robbery, Dominguez spent more than $50,000 in cash on a motorcycle, a new car and an hydraulic ironworking machine, according to the indictment.