Long after federal prosecutors decided not to pursue criminal charges against then-Sheriff Dave A. Clarke Jr. over his treatment of a fellow airline passenger, an FBI agent's request to search Clarke's private gmail account was filed in federal court late Thursday.

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In a March 7 affidavit in support of a search warrant request, Special Agent Jennifer Walkowski lays out the well-publicized January encounter between Clarke and Dan Black, and the ensuing hassle Black was subjected to by deputies at Clarke's direction in the January incident.

By May, a federal prosecutor had informed Black's attorney that he saw no basis for a criminal civil rights violation charge.

Walkowski was seeking the warrant for information kept by Google about Clarke's email address, dclarke.cowboy@gmail.com. She notes the FBI began its investigation after getting the report of one done by the Forensic Audit Manager for the Milwaukee County Office of the Controller-Audit Services Division.

Walkowski asked that the warrant application be sealed since at the time the FBI investigation involvement wasn't known to possible targets. It sought all email activity records for the dclarke.cowboy account from Jan.15 and forward.

Black's civil rights lawsuit against Clarke remains pending in federal court.