The U.S. Border Patrol and local law enforcement agree that officers are not supposed to enforce immigration laws while on Operation Stonegarden shifts.

"We are looking for them to basically enforce those laws that are within their jurisdiction, their current scope of authority," said Paul Beeson, Border Patrol Yuma Sector Chief. "Those things that they can do that can provide for a safer border for all of us."

Nogales Police Chief William Ybarra says officers know who belongs in the area and who doesn't.

"We are not out there looking for your guy that is coming across to find jobs," Ybarra said. "We're not targeting any specific type of person. We are just looking for suspicious activity, things that don't appear to be right."

Border watch groups, however, fear the range of activities and lack of training blurs the line between state and federal policing.

"It's a recipe for racial profiling. It becomes an officer's own personal biases and assumptions," said Jennifer Allen, director of Tucson-based Border Action Network. "Here's this multimillion-dollar program and what it really boils down to is officer discretion. Is that what Operation Stonegarden is meant to be?"

Profiling also was a concern in Maricopa County, which doesn't get Stonegarden money because it is not a border county. After complaints that Sheriff Joe Arpaio directed deputies to search Latino neighborhoods for illegal immigrants based on skin color, federal authorities last month canceled the department's authority to conduct street-level immigration enforcement it held under a federal program called 287(g).

Stonegarden does not grant agencies the authority to enforce immigration law, but turning over illegal immigrants is common on Stonegarden shifts. Agencies in the Border Patrol's Tucson Sector, which covers from New Mexico to Yuma County, referred 8,088 illegal immigrants to the Border Patrol since October 2008, Border Patrol figures show.

"For our deputies, our function is we're looking to apprehend and refer illegal entrants, anything that has to do with border-related crimes," said Santa Cruz County sheriff's Lt. Raoul Rodriguez.

Immigrants rights' groups complain about racial profiling any time officers focus on cross-border crime, say Bisbee Police.

"The racial profiling thing is a seed that people like to plant just to disrupt something that is working," said Sgt. Benjamin Reyna.

Tucson police officers don't actively look for illegal immigrants on Stonegarden shifts, said Lt. J.T. Turner.

"Immigration status of these people really is irrelevant," Turner said. "Our goal is to use this additional funding to enhance the safety of our community because it's deeply impacted by the transnational crime and the drug trafficking."

If officers on a Stonegarden shift come across someone they suspect is an illegal immigrant, they follow the agency's regular policy. They call the Border Patrol but wait as long as it takes to complete paperwork on the violation, or a "reasonable" amount of time, said Tucson Police Capt. George Rodriguez. If a Border Patrol agent doesn't come by then, police release the person.

But during Stonegarden shifts, the Border Patrol puts agents on standby close to Tucson, Rodriguez said, increasing the likelihood that an illegal immigrant will not be released.

Injecting local officers into the federal government's mission can cause confusion among residents about whom to trust, Allen said. For example, in New Mexico in 2007, Otero County sheriff's deputies used Stonegarden shifts to conduct raids in clusters of low-income family homes, interrogating Latino residents about their immigration status, according to a lawsuit filed by the Border Network for Human Rights. A federal judge barred the Otero Sheriff's Department from conducting immigration enforcement through Operation Stonegarden.

There haven't been similar incidents, but the possibility exists for civil-rights violations, said Heather Williams, a federal public defender for Arizona.

"This sure sounds like an increased license to bother local people," Williams said.