Zachary Foxx was one of Jerry Orbach's earlier roles long before Beauty and the Beast and Law & Order came out. It's a little hard to recognize his younger voice without the New York accent and trademark snark that made Lenny Briscoe a star, but it's the same guy.
Talking to Himself: Henry Mandell did an amazing amount of voices, especially for secondary characters. The Screen Actors Guild had rules for overtime, but being as Henry was a series producer and the creator's brother...
What Could Have Been: In the initial demo reel (included on the DVD box set), Zachary's children were also captured and implied to have shared in their mom's Fate Worse Than Death. The demo reel also featured different (and to this day unknown) actors playing Zach and the gang.
The writers admit that they would have jumped at the chance to write in an excuse for Zach to sing, seeing as Jerry Orbach was a Broadway veteran.