The Republican & Herald newspaper reports the probe began last week after the Schuylkill County prison board suspended three corrections officers with pay for undisclosed reasons.
The suspensions came the same week a consultant's internal report on the prison found ethics violations. The nature of the violations was not disclosed.
Pottsville police Chief Joseph H. Murton V said Monday he wants the criminal probe to finished as soon as possible.
One prison guard was fired in September amid a sexual harassment investigation.
Information from: Pottsville Republican and Herald, http://www.republicanherald.com