Video cameras in hand, Jason Aragón and Lynda Cruz rush to the scene of a suspected civil-rights violation.

"Is BP on the way?" Cruz asks as she texts a message to 35 fellow volunteers, asking if the Border Patrol is headed to the same place they are, about two miles away.

It's another night on the cop watch for Aragón and Cruz, members of a coalition of Tucson civil-rights organizations that fear Arizona's tough new immigration law could lead to racial profiling by police and referrals to the Border Patrol despite local law enforcement's assurances to the contrary.

Through the "Yo Soy Testigo" campaign - "I Am A Witness"- the groups use video cameras to document traffic stops in hopes of ensuring the civil rights of arrestees are not violated when border agents might be called in.

Learn more about the campaign in a story that runs exclusively in today's print edition of the Arizona Daily Star.

Pick up a copy of today's Star at all convenience, drug and grocery stores in the Tucson area or subscribe here. If you're outside Southern Arizona, order an electronic edition delivered to your inbox each day - complete with advertisements and useful search function.