As immigrant rights activists gear up to protest Obama’s deportation record in dozens of cities this weekend, Maricopa County Sheriff Joe Arpaio voiced a different set of concerns with this administration’s immigration enforcement.

When unauthorized immigrants wind up in jail, they may be turned over to Immigration and Customs Enforcement. And that agency might put them in deportation proceedings.

But Arpaio is worried the system isn’t working right.

“My concern is that when we turn the inmates over to ICE for deportation, that in the past years, several times they have come back,” Arpaio said. “So evidently they are actually let out the back door, or they are deported, and come back across that border many, many times.”

Arpaio said he did a survey of 1,348 immigrants detained in his jail without papers and found 419 had previously been charged with state crimes.

Arpaio has sent a letter to Secretary of Homeland Security Jeh Johnson, asking for an explanation of how the federal government handled those 419 cases.

KJZZ could not immediately verify whether all those individuals met the federal government’s deportation priorities.

The Phoenix ICE office deported almost 35,000 immigrants last year, including more than 21,000 convicted criminals.