Christopher Simmons was 17 years old and a junior in high school when he committed the murder of Shirley Crook in Missouri. Simmons planned the crime with two friends, Charles Benjamin and John Tessmer, discussing breaking into a home, tying up a victim, and throwing the victim off a bridge. On the night of the murder, Simmons and Benjamin entered Crook's home through an open window, bound her with duct tape, drove her to a state park, reinforced her bindings with electrical wire, wrapped her face in duct tape, and threw her from a railroad trestle into the Meramec River, where she drowned.
Simmons was arrested the next day at his high school after bragging about the killing. Police read him his Miranda rights, and he waived his right to an attorney before confessing and agreeing to a videotaped reenactment at the crime scene. The State charged him with burglary, kidnapping, stealing, and first-degree murder. Because Simmons was 17 at the time of the crime, he fell outside Missouri's juvenile court jurisdiction under Mo. Rev. Stat. §§ 211.021 and 211.031 and was tried as an adult.
At trial the State introduced Simmons' confession, the videotaped reenactment, and testimony about his advance planning and later bragging. The defense called no guilt-phase witnesses. The jury convicted Simmons of first-degree murder. In the penalty phase the State presented victim-impact testimony from Crook's family and proved three aggravating factors. The defense presented testimony from Simmons' family and a juvenile justice officer about his lack of prior record and family relationships, and both sides addressed his age as a mitigating factor. The jury recommended death, and the trial judge imposed it.
Simmons obtained new counsel and moved for postconviction relief, arguing ineffective assistance because trial counsel had not presented evidence of his immaturity, impulsiveness, difficult home environment, substance abuse, and poor school performance. The trial court denied the motion. The Missouri Supreme Court affirmed the conviction and sentence on direct appeal and the denial of postconviction relief. Federal habeas relief was also denied. After this Court decided Atkins v. Virginia in 2002, Simmons filed a new state postconviction petition arguing that Atkins required the same categorical exemption for juvenile offenders. The Missouri Supreme Court agreed, set aside the death sentence, and resentenced Simmons to life imprisonment without parole. The U.S. Supreme Court granted certiorari.