Feds cleared Arizona sheriff, then started investigation

Attorney General Eric Holder has made a public spectacle of suing Arizona for enforcing law and, separately, Maricopa County Sheriff Joe Arpaio. Holder is investigating Sheriff Arpaio despite a prior investigation giving his force and their operation a clean bill and high marks. So why is Holder investigating? Chicago politics? Bryon York describes the prior investigation by ICE - Immigrations and Customs Enforcement. Washington Examiner

... ICE officials evaluated how the sheriff's office performed under a law that allows specially trained local law enforcement officers to enforce parts of federal immigration law. The Maricopa County Sheriff's Office, which is the largest sheriff's office in the Arizona, has 189 officers who have been trained by ICE to enforce federal immigration statutes. The report, crammed with acronyms and bureaucratese, is not light reading. But struggle through it, and the key sentence is this: "The OI and DRO supervisors consider the conduct and performance of the MCSO ... officers to be professional and meeting the requirement of the MOA." Translated, that means officials from the Homeland Security Department's Office of Investigation (OI), along with officials from the Detention and Removal Operations office (DRO), concluded that the Maricopa County Sheriff's Office (MCSO), in its handling of illegal immigrants, acted in a professional manner and complied with a memorandum of agreement (MOA) under which the government gave them the authority to enforce federal law. That agreement included a ban on racial profiling. ICE investigators also interviewed top federal officials involved in illegal immigrant cases in Arizona. They found an "excellent" working relationship between the sheriff's office and the feds. ICE talked as well to federal prosecutors in Phoenix, who described the cases brought by Maricopa County as "high quality." In all, it's a quite positive assessment of an operation that just six months later would come under the Justice Department's microscope for alleged civil rights violations. It also lends indirect support to Arpaio's contention that the Justice Department investigation is politically motivated.

Show us the data, Mr. Holder. All of it. Why does the investigation with high marks lead to a new investigation?