Nick & Nora-Who was the murderer?

I was wondering if there was anyone on here who saw Nick & Nora, and remember what the ending was and who the murderer or murderers were? On my first trip to nyc when I was a freshman in high school I wanted to see it very much because I loved Joanna Gleason, unfortunately through some circumstances, I was not able to see it, and my first Broadway show was Park Your Car In Harvard Yard instead. About a week later, Nick & Nora closed. I realize it was panned, and most people who saw it hated it. I enjoy the cd, and love the window card which sits in my apartment framed. I have messaged some people who have seen it, and they just simply cant remember what happened at the end...(i guess it was that bad)...but if anyone can remember, I would love to finally know, years later, who the culprit was!:)
Thanks!

Okay..that was funny!

It was **Spoiler** -
Tracy Gardener (Christine Baranski's role)