An inmate in Butler County's jail faces charges that he possessed a cellphone with a SIM card, which is illegal.

William Kelly Penn, 36, is a federal inmate being held in Butler County Prison. The indictment was filed April 21. Penn is scheduled to appear for a hearing on the case on April 29.

Charging documents do not include what Penn was originally being held for in the jail. According to court records, authorities discovered Penn had the prohibited cellphone on Feb. 20.

The investigation was conducted by the U.S. Marshals Service. Penn could face up to one year in prison, a fine of up to $100,000, or both. Prosecutors could not be reached for comment.

Court records state that Penn's first offense occurred in Allegheny County.

During the most recent Butler County Prison Board meeting last month, Warden Joe DeMore marveled at the number of federal inmate transfers who were coming into the county jail with cellphones. He noted that many of the federal inmates were surprised to learn they couldn't possess a cellphone. A majority of the federal inmates are arriving from a private prison, Northeast Ohio Correctional Center.

DeMore said during that jail board meeting that the rise of federal inmates was attributed to a recent policy decision by President Joe Biden to reduce the number of inmates being held in privately-owned correctional facilities. The federal government pays the county $75 per day for each inmate.