Should I write the scene our leave it a mystery?

I am writing a sort of mystery suspense drama. One of my charters is a killer the other is hell bent on proving that he is the killer. I was thinking about writing the charters kill scene mainly in effort to let my readers know how the evidence my seconde character will find later proves his guilt. Our maybe I should let the readers find out when the other character does. What is your opinion? Thank you!