Shawn Ryan Grell, a 50-year-old man convicted of murdering his 2-year-old daughter in 1999, died in a Tucson prison on April 19. Grell had doused his daughter with gasoline and set her on fire in a desert near Mesa, leading to her death.

Initially sentenced to death, his sentence was changed to life in prison in 2013 after the Arizona Supreme Court ruled he had mental retardation, prohibiting execution under federal law.

The cause of his death is under investigation, as is standard for all inmate deaths.