RIVERSIDE, Calif. -- A former special agent with U.S. Immigration and Customs Enforcement has been arrested on suspicion of sexually assaulting two women and using his position to make sure they didn't report the crimes.Authorities say John Olivas of Riverside was arrested Wednesday and pleaded not guilty to federal civil rights charges of deprivation of rights under color of law.Olivas could face a potential life sentence if convicted. He's free on $50,000 bond.Prosecutors say Olivas tried to rape a woman and twice raped another woman in 2012 while he was a special agent for ICE homeland security investigations.In both cases, prosecutors said Olivas told the women that police wouldn't respond to any crime reports they made because Olivas was a federal law enforcement officer.