In a motion for summary judgment filed Monday, federal prosecutors asked for an order requiring Arpaio to turn over files and allow investigators to inspect the jails in Maricopa County and question members of the sheriff's department. They also sought an order that the sheriff cooperate in the future.
The investigation into whether Arpaio and his department engaged in racial discrimination began in 2008. The Justice Department sued Arpaio earlier this month, charging that he has tried to stonewall the investigation.
Arpaio has not yet filed his response to the lawsuit.
The Justice Department is involved in a separate investigation into whether the sheriff's office has abused its power. That issue is now being considered by a grand jury.
Arpaio, a former Drug Enforcement Administration agent, has long been controversial. Most recently, critics say his sweeps looking for illegal immigrants in Arizona have been aimed at Hispanics.