One-time Miami social worker aide Grady Nelson admitted to raping and stabbing his stepdaughter and stepson, then gashing their mother more than 60 times -- including slashing her neck ``from side to side, right through the jugular,'' a prosecutor told jurors Wednesday.

``As if this wasn't enough, the person who killed her took a big butcher knife and jammed it into her skull,'' prosecutor Susan Dannelly said in opening statements in Nelson's murder trial.

Nelson, 52, is charged with first-degree murder, attempted murder and sexual battery. He is accused of killing his wife, Angelina Martinez, 32, in January 2005 inside their Miami house. He faces the death penalty -- one of the reasons it took six weeks to select a jury.

The Miami-Dade Human Services Department hired him in 2000 as a social worker's aide, despite a conviction for the 1991 rape of a 7-year-old neighbor.

By 2005, Nelson had been having sex with Martinez's mentally retarded 11-year-old daughter for years, Dannelly said. Shortly before the murder, he was briefly jailed for the sexual activity but prosecutors had to drop the charges because the girl gave inconsistent statements.

A judge signed a domestic violence injunction, but it came too late. Nelson went home after his release from jail, and the next morning police found him -- covered in blood -- inside the house, wielding a knife.

In a videotaped confession, Nelson admitted to Miami-Dade police detectives he had also stabbed and sexually assaulted the girl and Martinez's 13-year-old son that day, Dannelly said.

But defense attorney David S. Markus on Wednesday offered a different version of events. He said Nelson came home and discovered the bodies, and was coerced by police into giving a false confession. ``There is a lot more to this case than blood and guts,'' Markus said.

In his opening statement, Markus suggested the culprit was Andrew Hall, 62, the boyfriend of the children's grandmother. In an unrelated case, police arrested Hall in January after detectives said he admitted impregnating the girl in 2008.

Hall is awaiting trial. Prosecutors say there is no evidence Hall had sexual relations with the girl in 2005, or played any role in the slaying.