Michael D. Taylor was too young for a death sentence when he raped and murdered a classmate at McCluer North High School in 1995, but later went to death row for a prison killing.
On Tuesday, a divided Missouri Supreme Court ordered a new sentencing hearing in the capital case, with a new set of jurors.
Writing for the majority, Chief Justice Laura Denvir Stith said that prosecutors failed to provide the defense with evidence that might have challenged the credibility of a prison informer.
Joined by Judges Richard Teitelman and Michael Wolff, Stith also wrote that the defense could have put on evidence in the penalty phase of the trial about severe abuse Taylor suffered as a child and his mental state at the age of 11 or 12, when the family attempted a church exorcism because the boy said he was hearing the voices of demons.
In the guilt phase, the jury had heard testimony of five mental health experts for Taylor, who attested to his mental illness. Three experts for the state suggested Taylor was faking it.
Also testifying was an inmate at the prison in Potosi, Scott Perschbacher, who claimed he had read a note as it passed from one cell to another, in which another prisoner urged Taylor to "continue the nut role and doing crazy things so they will think he's crazy."
The high court said the prosecution never provided the defense before trial with letters Perschbacher wrote to an investigator, with information that Perschbacher had made false accusations against police, or that the state planned to give him favorable treatment in a pending case if he gave helpful testimony.
Because Taylor had called guards to his cell and admitted strangling his cellmate, Shackrein Thomas, the court concluded 6-0 that the guilty verdict should stand.
Judge William Ray Price Jr., joined by Judge Mary Rhodes Russell, wrote that Perschbacker's credibility had been challenged on other grounds during cross-examination and that the defense attorneys had made a strategic call in not putting on additional evidence about Taylor's mental problems. They would have let the death penalty stand.
Judge Lawrence E. Mooney, an appellate judge sitting on the case, concurred in the results only.
Taylor was 48 days short of his 16th birthday when he beat, raped and drowned McCluer freshman Christine Smetzer in a restroom at the school in Florissant on Jan. 24, 1995. The minimum age for a death sentence in Missouri was than 16. He was sentenced in 1998 to life in prison without parole.
A year later, he strangled Thomas. Taylor got a death sentence in a trial in 2003 held on a change of venue in St. Charles County Circuit Court.
The case is unrelated to that of Michael A. Taylor, who is on Missouri's death row for the murder of a girl, 15, in Kansas City in 1989.