The mother of the 45-year-old man accused of lighting a blowtorch and scorching his parents and seven other relatives in Puerto Rico died Tuesday in the Río Piedras Medical Center.
According to El Nuevo Día, a newspaper in Puerto Rico, Josefina Díaz, 86, was in critical condition after she sustained burns on 40 to 50 percent of her body.
Her son, Justino Sánchez Díaz, now faces murder charges by the Puerto Rico Justice Department for his mother's death. He is also accused of killing his 17-year-old niece, Pamela Sanchez Vazquez, and his 32-year-old cousin, Samuel Molina, who both died from their burns. Six others were also injured in the attack.
El Nuevo Día reports that three of those six are suffering from burns on 60 to 80 percent of their bodies.
Police say Sánchez sprinkled gasoline around a room at his parent's home on Saturday in the northern town of Florida, and then set it on fire with a blowtorch as 13 family members gathered for dinner on New Year's Day. The motive for the alleged attack is unknown.
The Associated Press contributed to this article.