Two Suffolk corrections officers pleaded not guilty Thursday to assaulting an inmate at the county jail in Riverhead in 2013.

Vincent Cennamo and Mark Nicol are accused of attacking Joshua Durkel, who was serving a sentence for a probation violation after a drug conviction.

Prosecutors say Cennamo filed a false report saying Durkel, 32, slipped and suffered a cut above his right eyebrow when he hit his head on a stove.

Following a two-year investigation, a grand jury handed up an indictment Thursday. Cennamo was charged with assault in the third degree, falsifying business records, offering a false instrument for filing and official misconduct. Nicol was charged with assault in the third degree.

Both officers have been suspended without pay. They were released on their own recognizance and are scheduled to return to court on March 21.