The sheriff's office in neighboring Pinal County agreed to look into the memo, which reportedly warned that Maricopa County Sheriff Joe Arpaio was using the unit to conduct surveillance of his political opponents.
The 63-page memo was revealed this week in the Arizona Republic. It was written by Maricopa Deputy Chief Frank Munnell and alleged mismanagement on the part of Chief Deputy Dave Hendershott and two other top officials.
Hendershott has been on medical leave while recovering from surgery. Deputy Chief Larry Black and Capt. Joel Fox were placed on administrative leave this week.
Sheriff's Lt. Brian Lee said Arpaio immediately called for an investigation by an outside agency. "We're bending over backward, trying to ensure everyone we're doing what we're supposed to do," Lee said Friday.
The Los Angeles Times Saturday called the Pinal County sheriff, Paul Babeau, a political ally of Arpaio. At least two county supervisors said Friday the FBI should take over the probe.
Arpaio has long been a political hot potato in Phoenix for his hard line on illegal immigrants and the relatively harsh conditions in the Maricopa County jail system.