DOVER, Del. — A former Delaware prison guard charged with smuggling drugs and cellphones to inmates at the maximum security prison in Smyrna in return for bribes has agreed to enter a guilty plea in the case.

A federal judge on Wednesday scheduled a change of plea hearing for May 30 for Thomas Nadill Boyce Jr.

Boyce and fellow guard Paul Hursey were charged last year with extortion.

A third guard, Lorraine Mosley, also was charged last year with smuggling a cellphone to an inmate at the women’s prison in New Castle in return for a bribe.

Boyce is accused— in court documents— of conspiring with inmates and their associates to smuggle cellphones, heroin, and marijuana into the prison in exchange for money.