Oakland’s police chief is facing an internal affairs investigation, a formal complaint by a city commissioner and questioning by furious City Council members --- all because she—perhaps unwittingly—helped federal authorities arrest an illegal immigrant in a sanctuary city.

Anne Kirkpatrick, who was widely heralded as a seasoned progressive reformer when she became Oakland’s top cop early this year, has acknowledged that she sent police officers to assist federal agents for a human trafficking investigation at an Oakland home Aug. 16.

Two adults were detained during that investigation, and federal authorities have commenced civil deportation proceedings against one of them, according to SFGate.

The episode touched off a furor in Oakland, where policy precludes cooperation with federal immigration authorities and the City Council in July unanimously ended its already-limited involvement in federal task forces.

Kirkpatrick insisted at a town hall in September that she told federal agents the day before the August operation that her officers would not participate in any arrests, the East Bay Times reported. Oakland police merely blocked the streets during the federal agents’ operation, Kirkpatrick said in a written response to City Council members, SFGate reported.

“There is not a deportation matter in this case," Kirkpatrick assured attendees at the town hall.

Kirkpatrick’s explanation did not sit well with Oakland officials.

Brian Hofer, the chairman of Oakland’s Privacy Advisory Commission, filed a formal complaint against Kirkpatrick with the police department’s internal affairs division, according to SFGate.

The complaint, which seven others joined, centers on both Kirkpatrick’s statements surrounding the operation and city authorities’ involvement in the arrests.

Oakland police described the operation as a sex trafficking investigation on Aug. 16, before later calling it a human trafficking probe, according to SFGate.

Oakland Councilwomen Desley Brooks and Rebecca Kaplan have pressed Kirkpatrick for more answers, according to SFGate.

Oakland police confirmed to the Oakland Tribune that their internal affairs division would investigate Kirkpatrick.