From this:

...During a large protest on Saturday in Phoenix that drew 10,000 people, immigrant-rights advocates called on the Department of Homeland Security to end (the 287g program), saying some Valley police officers are engaging in racial profiling by arresting Latinos for minor crimes in order to check their immigration status during the booking process.

But John Morton, the assistant secretary for Immigration and Customs Enforcement (of the Department of Homeland Security), said that is "not in practice what we have seen in the program" known as 287 (g).

Furthermore, he said that while the agency places a priority on arresting illegal immigrants who commit serious crimes, it also cannot turn "a blind eye to people who are here unlawfully simply because they don't have a criminal record."

..."Sixty nine percent of the people we receive in Maricopa County have been convicted of Level 1 and Level 2 offenses, which are serious felony offenses, drug trafficking, assaults, rape," Morton said...

More than 90 percent of the cases presented to the U.S. Attorney in Arizona involving people who committed a felony crime of re-entering the U.S. after deportation from the Maricopa County jail, Morton added.

It was Morton who ended Arpaio's ability under 287g to perform proactive neighborhood sweeps, but he kept in place the jail checks under the same program.

Note also that the Department of Justice is currently conducting a witchhunt against Arpaio but, instead of trying to go after him for racial profiling, they've elected to try to go after him for abuse of powers unrelated to immigration enforcement.