In this file photo, death row inmate Juan Carlos Chavez is shown during the first day of hearings at a Miami-Dade County courtroom in Miami. Picture: Alan Diaz, File

Starker, Florida -

A US man who raped and killed a nine-year-old boy 18 years ago, spurring the boy's parents to work for enhanced sexual predator confinement laws, is scheduled to die on Wednesday by lethal injection.

Juan Carlo's Chavez is scheduled for execution at 6pm at Florida State Prison in Starker, Florida.

Chavez abducted Jimmy Ryce at gunpoint after the boy got off a school bus on September 11, 1995, in rural southwestern Miami-Dade County. Trial testimony showed Chavez raped the boy and then shot him when he tried to escape, dismembering his body and putting the parts in concrete-covered planters.

Despite an intensive search by police and volunteers, regular appeals for help through the media and distribution of flyers about Jimmy, it wasn't until three months later that Chavez's landlady discovered the boy's book bag and the murder weapon - a revolver Chavez had stolen from her house - in the trailer where Chavez lived. Chavez later confessed to police and led them to Jimmy's remains.

He was found guilty of murder, sexual battery and kidnapping.

Chavez's most recent round of state and federal court appeals have focused on claims that Florida's lethal injection procedure is unconstitutional, that he didn't get due process during clemency hearings and that he should have an execution stay to pursue additional appeals in the federal courts.

Ryce's death led to changes in the legal system, and the way police respond to missing child cases.

Don Ryce, Jimmy's father, said recently that he and his wife became determined to turn their son's horrific slaying into something positive, in part because they felt they owed something to all the people who tried to help find him. They also refused to wallow in misery.

“You've got to do something or you do nothing. That was just not the way we wanted to live the rest of our lives,” he said.

The Ryces created the Jimmy Ryce Centre for Victims of Predatory Abduction, a nonprofit organisation based in Vero Beach that works to increase public awareness and education about sexual predators, provides counselling for parents of victims and helps train law enforcement agencies in ways to respond to missing children cases. - Sapa-AP