Every person indicted for a crime or offense may peremptorily challenge 12 of the jurors impaneled to try him. The state shall be allowed one-half the number of peremptory challenges allowed to the accused; provided, however, in any case in which the state announces its intention to seek the death penalty, the person indicted for the crime may peremptorily challenge 20 jurors and the state shall be allowed one-half the number of peremptory challenges allowed to the accused.