SAN DIEGO (CNS) - Eighteen additional charges were filed Tuesday against two parolees suspected in a series of "high-risk" armed robberies throughout California last year, including one at a Fashion Valley jewelry store and another at the Barona Casino.

Robert Chavira, 40, and Ryan Alan McKnight, 34, were charged in November with one count each of robbery and arson. Charges of conspiracy, false imprisonment, robbery and assault with a deadly weapon were added Tuesday.

Deputy District Attorney Rick Clabby told Judge David Szumowski last year that Chavira and McKnight were involved in five "high-risk" armed robberies in Costa Mesa, Mission Valley, San Jose, Palm Desert and at the Barona Casino.

On Aug. 2, the armed defendants used sledgehammers to steal hundreds of thousands of dollars worth of watches from a Costa Mesa store, Clabby alleged.

On Sept. 12, they allegedly drove down a walkway at the Fashion Valley mall and used sledgehammers to break display cases and steal high-end Rolex watches from the Ben Bridge store.

Chavira and McKnight are accused of using the same tactic to steal Rolex watches from a high-end jewelry store in San Jose on Oct. 15, Clabby told the judge.

Nine days later, the defendants -- armed and wearing masks -- allegedly stole more than $1 million in Rolex watches from a store in Palm Desert.

Clabby said the defendants changed their method of operation when they allegedly stole $60,000-$70,000 from a glass case at the Barona Casino on Nov. 2.

The defendants set fire to a house next to the casino to draw firefighters and authorities away from the business, the prosecutor alleged. Clabby alleged that Chavira and McKnight tied a chain to the back of a vehicle and ripped out a glass case containing the cash.

A video shows McKnight buying gas before the fire was set, the prosecutor said.

When the defendants were arrested a week later, gear used to commit robberies was found in their hotel room, Clabby said.

A third defendant, 22-year-old Adrian Ramos, was charged in connection with the robberies at Barona, Fashion Valley and San Jose, according to a criminal complaint.

A status conference is scheduled Wednesday at the downtown courthouse.