My father was related to yours--a cousin, I think. Who was your paternal grandfather? I searched for many years for my father and finally found him in 1989. He has since passed away. When he was young, he, his brothers and cousins all seemed to have hung out in the East Chicago area. I don't think anyone would admit to actually knowing who killed your dad . I do know lots of Cornetts lived up there in the late 40s and early 50s and worked in the steel mills. and hung out together. What I am sure of is if any of the family knew who killed your dad, they would have taken care of it on their own--if you know what I mean. The Cornetts were a strong bunch and took care of their own family problems.
I feel your pain and if there is anything I can help you with, let me know. God bless you.