Authorities say a second inmate in less than a month has been killed by a cellmate at a maximum security prison in South Carolina.

The Corrections Department said in a statement that 24-year-old Ryan Mansfield was killed early Thursday in his cell at Lieber Correctional Institution near Ridgeville. Prison officials didn't say how Mansfield died.

Prison records show Mansfield was serving a five-year sentence for burglary and grand larceny and was due to be released in March.

Authorities say Mansfield was killed by another inmate, adding no charges have been filed so far. The investigation continues.

A prisoner was also killed by a cellmate at Lee Correctional Institution on June 22.