Excessive bail shall not be required, excessive fines shall not be imposed, and cruel and unusual punishments shall not be inflicted. It shall not be cruel and unusual punishment to impose the death penalty on a person convicted of purposely or knowingly causing death or purposely or knowingly causing serious bodily injury resulting in death who committed the homicidal act by his own conduct or who as an accomplice procured the commission of the offense by payment or promise of payment of anything of pecuniary value.