The investigation and possible prosecution of metropolitan Phoenix Sheriff Joe Arpaio will be handled by the U.S. Justice Department after federal prosecutors in Arizona asked to be removed because of unspecified conflicts of interest, according to a court filing made public Friday.

The U.S. Attorney's Office for Arizona said in its brief filing in U.S. District Court in Phoenix that the case has been assigned to the Justice Department's criminal division, public integrity section.

The filing cited "existing conflicts of interest or the appearance of conflicts of interest pertaining to the matter" for Arizona's federal prosecutors, but it did not provide details.

Mel McDonald, an attorney for Arpaio, said he was disappointed by the decision.

"It's their call," McDonald said. "If they have a conflict ... I'm not one to second-guess that decision."

U.S. District Judge Murray Snow ruled last Friday that another judge should decide if Arpaio and others should be held in criminal contempt-of-court for ignoring court orders in a racial profiling case. Snow also said there was probable cause to believe Arpaio intentionally failed to turn over records that he had promised, under oath, to give to a court official.

The records were from a secret investigation that Arpaio's foes say focused on Snow in an attempt to discredit him.

Arpaio, a Republican who is running for a seventh term this year, has vigorously insisted that he didn't investigate Snow and instead said the probe was focused on widespread identity theft.

Snow has not publicly explained why he turned the Arpaio case over to another judge, but federal law says a judge is to be disqualified from a criminal contempt case if the defendant is accused of disrespecting or criticizing the court.

Snow also wanted another judge to determine whether sheriff's Chief Deputy Jerry Sheridan, Capt. Steve Bailey and former Arpaio attorney Michele Iafrate violated orders in concealing nearly 1,500 IDs in an internal investigation into whether officers pocketed items from people during traffic stops.

In May, the judge found Arpaio, Sheridan and two other sheriff's employees in civil contempt of court for violating three orders within the nearly 9-year-old profiling case. Arpaio and Sheridan were previously found to have made several intentional misstatements of facts last year during their contempt hearings.

Three years ago, the sheriff's office was found to have racially profiled Latinos in regular traffic and immigration patrols.

Snow imposed a series of changes aimed at guarding against profiling, but he has complained that Arpaio has been slow to make the changes.

Arpaio, 84, built his political reputation on pushing the bounds of local immigration enforcement, making inmates wear pink underwear and jailing them in tents during Phoenix's triple-digit summer heat.

He voluntarily gave up his last major foothold in immigration enforcement in January 2015 after the courts and federal government gradually reined in his powers.