Washington (CNN) -- Justice Department civil rights lawyers filed suit against Sheriff Joe Arpaio of Arizona on Thursday after talks collapsed on a deal to provide federal investigators with requested documents. The suit, filed in federal court in Phoenix, Arizona, claims the Maricopa County sheriff has failed to cooperate with the investigation into alleged discrimination against Hispanics by Arpaio's law enforcement officials.
The federal action became virtually certain after the sheriff's office last Friday rejected the government's demands in an open letter posted on the county's website.
The Justice Department's Civil Rights Division is looking into claims the sheriff's immigration sweeps are discriminatory. Arpaio's attorneys have rejected the charge and offered limited access to documents it believes are relevant to the probe.
Arpaio is expected to announce Thursday he will fight the lawsuit.
Thursday's action marks the third lawsuit filed by the Justice Department against Arizona officials this month.
The government sued to block the state's new immigration law that permits officers to question people about their immigration status and request personal documents.
On Wednesday, the government sued Maricopa County's community college system for alleged employment discrimination against Hispanic employees.
