MADISON, Wis. (AP) — The warden at a troubled Wisconsin prison has resigned amid lockdown conditions, an ongoing federal investigation and multiple inmate deaths.

Waupun Correctional Institution Warden Randall Hepp announced his resignation on Tuesday, the Wisconsin State Journal reported. The newspaper obtained an email Hepp sent to prison staff in which he wrote his decision wasn’t easy but he believes it will serve the institution well. He added that the prison has moved closer toward improving safety.

No one immediately responded to an email The Associated Press sent to state Department of Corrections media officials and Gov. Tony Evers spokesperson, Britt Cudaback on Sunday morning seeking comment.

Brad Mlodzik, who previously worked as deputy warden at Waupun, will take over as warden there on June 30, the State Journal reported.

A chronic lack of guards forced the state Department of Corrections to institute a lockdown at Waupun as well as at prisons in Green Bay and Stanley. Waupun inmates filed a federal lawsuit in October alleging the conditions amounted to cruel and unusual punishment. That lawsuit is still pending. Stanley resumed normal operations in late November. Movement restrictions have eased at Waupun and Green Bay, but some remain in place.

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Cudaback, Evers’ spokesperson, said in March that federal authorities are investigating an apparent smuggling ring involving Waupun Correctional employees. She said then that multiple sweeps of the prison revealed people were obtaining prohibited items such as cellphones and illegal drugs. At least 11 prison employees have been suspended since May 2023 in connection with the probe.

Four inmates have died at Waupun since June 2023. One killed himself in solitary confinement, one died of a fentanyl overdose and another died of a stroke. The fourth inmate was found dead at the facility in February. His death remains under investigation. The daughter of the inmate who killed himself in solitary confinement has filed a federal lawsuit alleging Waupun officials failed to provide him with adequate mental health care and medication.

Hepp took over as warden at Waupun in May 2020. He began his career in the state prison system in 1984 as a guard at Dodge Correctional Institution.