A Las Vegas man pleaded guilty to second-degree murder by child neglect for failing to seek prompt medical treatment for his girlfriend's ailing 3-year-old son in June 2005.
Jose Luis Rubio agreed to the plea Tuesday while jury selection for his trial was under way.
Rubio originally was charged with first-degree murder by child abuse.
Authorities said Rubio was caring for Joseph Rivera on June 13, 2005, when he contacted the boy's mother because the child was ill.
Rubio drove the boy to his mother, who was at work at Mandalay Bay, passing several hospitals along the way, authorities said. The boy was eventually taken to a hospital, where he died.
Investigators determined the child died from a recent severe blow to his abdomen that ruptured his pancreas.
Rubio will be sentenced Nov. 5 by Judge Donald Mosley. A charge of second-degree murder carries a 10- to 25-year prison sentence with the possibility of parole after 10 years.