MADISON, Wis. (AP) — Federal authorities have been investigating an apparent smuggling operation involving employees at a troubled Wisconsin prison, Gov. Tony Evers’ office said Thursday.

The probe has resulted in the suspension of nearly a dozen Waupun Correctional Institution employees to date, according to the state Department of Corrections.

The Milwaukee Journal Sentinel first reported the investigation. Evers spokesperson Britt Cudaback told The Associated Press in an email Thursday that the governor and Department of Corrections officials asked the U.S. Department of Justice and other federal authorities in June 2023 to launch the probe.

Cudaback said that they made the request after multiple sweeps of Waupun housing units revealed people in the prison were obtaining prohibited items such as cellphones and illegal drugs. An initial investigation by the Department of Corrections uncovered allegations that prison employees were involved, including information suggesting “financial crimes” may have occurred, Cudaback said.

She did not elaborate on the nature of those allegations and didn’t immediately respond to a follow-up email seeking details.

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The governor and the Department of Corrections decided to ask federal authorities to investigate given the potential involvement of employees and the multi-jurisdictional nature of the allegations, Cudaback said.

According to the Department of Corrections, 11 prison employees have been placed on administrative leave since May 2023. Three of them were placed on leave without pay; the others were placed on leave with pay. Any roles in the alleged smuggling ring were unclear.

A U.S. Department of Justice spokesperson didn’t immediately respond to an email Thursday seeking comment.

Four inmates have died at Waupun since June. The first was Dean Hoffmann, who killed himself in solitary confinement that month. Tyshun Lemons died of a fentanyl overdose on Oct. 2 and Cameron Williams died of a stroke on Oct. 30. Donald Maier was found dead at the facility on Feb. 22. His death remains under investigation.

The Department of Corrections instituted lockdowns at Waupun as well as at prisons in Green Bay and Stanley last year due to a shortage of guards.

A group of Waupun inmates filed a federal lawsuit in October saying lockdown conditions at the facility amount to cruel and unusual punishment. And last month Hoffmann’s daughter filed a federal lawsuit alleging Waupun officials failed to provide her father with adequate mental health care and medications. Those cases are pending.

Stanley resumed normal operations in late November. Movement restrictions have eased at Waupun and Green Bay, but some remain in place.