Sheriff Arpaio's office has filed a public-records request to Phoenix officials for information on Mary Rose Wilcox and her husband, former state law

A Maricopa County supervisor and frequent critic of Sheriff Joe Arpaio is under criminal investigation by the sheriff's office.

The Arizona Republic reports Arpaio's office has filed a public-records request to Phoenix officials for information on Mary Rose Wilcox and her husband, former state lawmaker Earl Wilcox.

Arpaio told the Republic last night the probe is a straightforward criminal investigation.

The sheriff's office also was involved in a criminal investigation into county Supervisor Don Stapley, who was indicted in December related to possible misstatements and omissions in his financial-disclosure forms.

The sheriff's office asked the Phoenix Aviation Department for documents related to the process that awarded a concession contract to the couple and their businesses, the El Portal restaurants and Chili's Too at Sky Harbor International Airport.

Wilcox says Arpaio is trying to intimidate her with a "vendetta" over her criticism of the way he enforces immigration.