Did anyone know the answer?

Lately I realized that I was too fixated on this case. I hate the trait that so strongly attracts me to secrets. I think this case cannot be solved with ordinary efforts.Of course, I hate to realize this, but I think I will be checking the status of this case for a very long time. I think the only way we could find out who Cooper was is from the words of those who knew it. Did Cooper tell anyone about his intentions? Did he survive? If there was someone who knew the truth, Such a person would be the only chance for us.