( CNN ) -- The Justice Department is preparing to sue Arizona Sheriff Joe Arpaio , known internationally as `` America 's toughest sheriff , '' saying talks between the two sides have fallen through . The Obama administration and Arpaio 's Maricopa County Sheriff 's Office had been in the midst of settlement talks , after the Justice Department accused it of systematically discriminating against Latinos . As part of the settlement , the department wanted Arpaio to allow an independent monitor to oversee reforms at his office . The Justice Department called it a `` key , non-negotiable requirement . '' The two sides were scheduled to meet Wednesday , but Arpaio called off the meeting at the last minute , the Justice Department said . `` We believe that you are wasting time and not negotiating in good faith , '' said Deputy Assistant Attorney General Roy Austin Jr. in a letter to Arpaio 's legal counsel . It added : `` MCSO 's refusal to engage in good faith negotiations requires us to prepare for civil action . '' Arpaio shot back , saying he would not `` surrender '' his officer to the federal government . `` Appointment of an outside monitor essentially usurps the powers and duties of an elected Sheriff and transfers them to a person or group of persons selected by the federal government , '' he said in a statement Tuesday . `` And so to the Obama administration , who is attempting to strong arm me into submission only for its political gain , I say , 'This will not happen , not on my watch ! ' '' A federal Department of Justice investigation into Arpaio 's office made public in December described `` a pervasive culture of discriminatory bias against Latinos at MCSO that reaches the highest levels of the agency . '' Arpaio dismissed the allegations as a politically-driven `` witch hunt . '' He pointed out how President Barack Obama opposed Arizona 's controversial anti-immigration law and how the president mentioned Arpaio as the person pushing the law , the sheriff said . `` By the way , I do n't want to say it 's all politics , but everyone I 'm talking about happens to be Democrats , '' said Arpaio , a Republican . Arpaio added : `` Do n't come to use me as a whipping boy for a national , international problem . '' The 22-page Justice Department letter alleged the Maricopa County Sheriff 's Office committed federal and constitutional violations . Detention officers in Arpaio 's jail invoked offensive slurs and profanities against Hispanics , calling them `` wetbacks , '' `` Mexican bitches , '' and `` stupid Mexicans , '' the letter said . `` Sheriff Arpaio 's own actions have helped nurture MCSO 's culture of bias , '' said the letter , written to the Maricopa County attorney . For example , the sheriff apparently endorsed one constituent 's letter asking for a `` round-up '' at one Phoenix street corner of `` dark-skin ( ned ) '' people : Arpaio told a member of his command staff in a note to `` ( h ) ave someone handle this , '' the Justice Department said . Jack MacIntyre , Arpaio 's deputy chief , described the Justice Department 's allegations as `` a sneak attack by the federal government on the citizens of Arizona . '' The Justice Department also said it is reviewing allegations that the sheriff 's office did not investigate `` a large number of sex crimes. `` The sheriff 's office has acknowledged to federal authorities that 432 cases of sexual assault and child molestation were not properly investigated over a three-year period ending in 2007 , and many of the victims apparently were Latinos , the Justice Department said . The federal findings also alleged discriminatory policing practices by Arpaio 's officers including `` unlawful stops , detentions and arrests of Latinos , '' according to a Justice Department statement . It also noted that the sheriff 's office has discriminated against `` Latino inmates with limited English by punishing them and denying critical services . '' It further blamed the office for allowing `` specialized units to engage in unconstitutional practices '' and for a lack of oversight and deputy training . The initial federal inquiry began in June 2008 and reviewed tens of thousands of pages of documents and more than 400 interviews , including current and former inmates as well as office personnel . Authorities notified the sheriff 's office of a formal investigation a year later , a statement said . Assistant Attorney General Thomas Perez said the sheriff 's office initially failed to cooperate with investigators , prompting federal authorities to take the `` virtually unprecedented step '' of filing a lawsuit in 2010 . He noted the investigation had uncovered startling levels of racial profiling against Latino drivers , ranging between four and nine times higher than against non-Latino motorists . Perez added that an independent reviewer involved in the probe described it as `` the most egregious racial profiling in the United States '' he had ever seen .
The two parties had been in the midst of settlement talks . The Justice Department wanted Arpaio to allow an independent monitor . Arpaio : ` ` This will not happen , not on my watch ! '' The suit alleges the governor 's office has committed constitutional violations .