Remember the first episode? With the suicide-serial killer? The creepy halloween toy maker named Milander? I remember in another episode Grissom finally realized his mistake in letting the creep go. Did he ever find the guy? I think i've seen every episode and I don't recall. I can't see Grissom leaving the show without solving the case that made the show!
Yes, they did catch him. He reappears that season in "Anonymous", which is where they figure out it was Millander. Then in the season two episode "Identity Crisis", they find him, confront him, and he commits suicide. His family is revisited later in season ten's "Ghost Town".