NASHVILLE, Tenn. — Tennessee prisons may have violated federal law by mishandling sexual assault cases and are experiencing staggering staff turnover rates at CoreCivic-operated facilities, according to an audit released Tuesday by the state's Department of Correction.

The audit, conducted by Tennessee's Comptroller's office, found multiple examples of the state's Department of Correction and CoreCivic staff violating federal Prison Rape Elimination Act standards, including closing sexual assault investigations before receiving rape testing results.

The department either didn't discipline or didn't document the discipline of at least four employees with "substantiated" allegations of sexual harassment against prisoners. In its formal response to the audit, Tennessee's Department of Correction pledged to provide "training for the appropriate staff" to improve compliance with the federal law.

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Massive spike in staff turnover

Meanwhile, systemic staffing issues are an ongoing concern, auditors found. The private prison operator CoreCivic saw massive increases in staff turnover during fiscal year 2023.

CoreCivic operated triple-digit turnover rates in its facilities, except for its Whiteville prison, a significant departure from its agreement with the state to keep turnover rates at 50% or lower, according to the audit. And the problem appears to be worsening, with CoreCivic facilities recording a 103% turnover rate in 2022 and a 146% turnover rate in 2023, the audit found.

CoreCivic's Trousdale prison is a major driver of these turnover issues, recording an 188% turnover rate in 2023, a 74% increase from 2022, the audit added.

The Tennessean, part of the USA TODAY Network, has reached out to CoreCivic for comment.

Meanwhile, the state's Department of Correction is seeking more than $9 million in budget increases in the upcoming fiscal year, more than $7 million of which is earmarked for CoreCivic. State-run prisons have improved their turnover rates in the last four fiscal years, dropping from 44% to 37% from 2020 to 2023, per the audit.

The audit found the state's Department of Correction management has "taken action" to address critical staffing issues, but prisons continue to face an "ongoing and deeply rooted challenge of attrition within their ranks."

Prisons have particularly struggled to staff correctional officer positions, which has led to entire housing units being staffed with a single officer, staff leaving doors that should be secured open for "convenience" and limited security during emergencies like fights and overdoses.

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Meanwhile, the department has relied on "unsustainable" levels of overtime to fill staffing gaps, the audit found. Tennessee's Department of Correction spent $51.4 million in correctional officer overtime over the past two fiscal years.

Sex abuse within federal prison system

While sexual misconduct in the prison system is underreported, a special report the Justice Department released earlier this year recorded thousands of victims of inmate-on-inmate abuse and staff-on-inmate abuse from 2016 to 2018.

The special report released in January found that staff sexual misconduct was underreported by inmates. Only about a quarter of incidents were reported by the victim, according to the report, and nearly 20% of the substantiated incidents were revealed through investigation or monitoring.

The federal prison system has faced widespread criticism after multiple incidents of staff sexual misconduct were revealed in recent years, including repeated incidents of inmate sexual abuse at a high-profile and all-female prison in Dublin, California.

Contributing: Thao Nguyen, USA TODAY