Execution in Colorado is by lethal injection and hasn't been carried out since 1997, when Gary Davis was executed for raping and murdering a woman in 1986.

WSJ: Death Penalty Sought in Colorado Shooting Trial

Execution in Colorado is by lethal injection and hasn't been carried out since 1997 on Gary Davis, who had been convicted of raping and murdering a woman in 1986.

WSJ: Holmes to Face Death Penalty in Colorado Shooting

In February, a judge ruled that convicted murderer Michael Morales could be put to death by lethal injection if a doctor monitored the execution.

NPR: Brain Waves Monitored During N.C. Lethal Injection