Corrections Secretary Gregg Marcantel told reporters Thursday that the investigation began after an unannounced team of investigators found guards with banned DVDs, cell phones, cooking equipment, and other electronics.
Guards aren't allowed to have any of the electronics in their possession while watching inmates.
Officials say a tip lead them to lock down the state penitentiary and find the contraband.
Marcantel says it's likely the guards responsible will be disciplined. He said random checks will become more frequent.