Their son, 39-year-old Michael Mears, died when Los Angeles police stunned him six times with a taser during a 2014 confrontation.
A coroner's report cited a heart problem but said cocaine and the use of the taser contributed to his death.
Mears had served in Somalia and Afghanistan and had suffered from PTSD. Police were called to his building on Christmas Eve 2014 when he was suffering from a PTSD episode, according to the attorneys for the Mears family.
Paramedics were unable to subdue him and called for help from police. The officers tried multiple times to subdue him, including using a baton and pepper spray.