I am trying to remember where it was that I saw a tv show or movie (lonnnngggg time ago) and I cannot remember. I know if anyone can help it would be someone here!

It was about an older man going to the police (?) station and confessing to multiple murders to a detective. When the detective asks him why he was confesisng he said that his friend and him had contest going, but now his friend was dead, there was no use. The detective then asks him if he would like a new opponent... and so it went....

If anyone can help me ID this one, I would very much appreciate it.