Records say 70-year-old Jose Alvarez died on Monday. How he died was not immediately clear.
Alvarez was facing charges in connection with the July 2023 shooting that killed his wife, Karina Gonzalez, and their 15-year-old daughter, Daniela, at a Little Village home.
Gonzalez was shot while she had an order of protection against Alvarez.
Karina's son, Manny Alvarez, survived the shooting.
SEE ALSO | 'Karina's Law' goes into effect in Illinois, son of domestic violence victim speaks out | EXCLUSIVE
Illinois Gov. JB Pritzker signed "Karina's law", named in her honor, in 2025.
The law requires guns to be removed from an accused abuser's home after a victim is granted an order of protection in a domestic violence case.