If a juvenile was charged in adult court with a death-penalty offense (first degree murder is the only one in Arizona), he or she could get the death penalty only IF the state asks for it and the court determined that enough aggravating circumstances exist to outweigh any mitigating circumstances, making that punishment appropriate for the individual convicted of that offense.

However, if the defendant was found by the court to be mentally retarded, then the death penalty is not usually available. Many states are reviewing their death penalty statutes to decide if they should refuse to allow the death penalty where the defendant is mentally retarded. Arizona is doing this review. Mental retardation is a substantial mitigating circumstance.

Also, if the defendant was under the age of 16 when the offense was committed, the death penalty is not available. The United States Supreme Court held that the death penalty cannot be applied to someone who was that young when they committed the offense. See the opinion at Thompson vs. Oklahoma, 487 U.S 815 (1988).

For more information on this issue, see:

Are they too young to die? MSNBC.