The head of Homeland Security Investigations (HSI) in Arizona says his team has sent about 15 cases to federal prosecutors in the roughly two weeks since U.S. Immigration and Customs Enforcement redirected agents to Yuma to probe whether migrants crossing the border are using fake documents to say they are families.

HSI agents have been sent to Yuma from ICE interior offices and human smuggling units. Victim assistance and forensic interview experts are also involved. But this means other cases are not getting the same attention, said Scott Brown special agent in charge for HSI in Arizona.

“We are having to steal from other program areas,” he said.

Migrants with fake birth certificates have been most common, Brown said. And agents have also come across people with real documents that have false information.

“It’d be like going to the DMV here and them issuing you a driver’s license with the wrong the name and the wrong date of birth,” he said.

A major success would be if HSI agents can find similarities in fake documents, then figure out who is providing them, and work with foreign governments to stop it, Brown said.