SIOUX FALLS, S.D. — A death row inmate in South Dakota expresses his frustration with delays in his execution in his first public comments since sentencing.

Fifty-year-old Eric Robert was sentenced to death in October after pleading guilty in the April 2011 slaying of prison guard Ron Johnson.

Robert's execution was scheduled for the week of May 13, but the state Supreme Court delayed it in February to allow more time for a mandatory review of the case — despite the fact that Robert wasn't contesting the sentence.

In a three-page letter to the Associated Press, Robert explains why he believes the death sentence is appropriate in his case and says that by delaying his execution, the court is delaying justice for the Johnson family.