Martin was one of several stars of the Broadway musical hired to reprise their roles in the film version, due in theaters Nov. 23.
"People come up and they say, 'Detective Green, I had no idea that you can sing,'" Martin told reporters in New York recently. "And the funny thing is that they used to say the very same thing to (my former co-star) Jerry Orbach. Jerry was the prince of New York theater and people didn't know Lennie Briscoe could sing."
So, does Martin think his character's romantic relationship with a bubbly transvestite will also surprise his fans?
"It's certainly different than anything they've seen me do on 'Law & Order,'" he admitted. "So, I'm excited about it. I'm very proud of it. So, they'll have to get ready for it because it's as big as life."