What is illegal? Not telling the JCC?
It's practically illegal to give a bad reference. I don't think you can offer information like that. If the organization had specifically asked if the guy had embezzled, I think they'd be within their rights to say "Yes" and that's about it.
I'm sure we could get a labor lawyer in here to correct me but I believe it's part of the Title legislation protecting Stupid People, thieves, insane people and fang-tooth bitches who file frivolous lawsuits against their employers ... stuff like that.
It's like using c-notes to scrape the gum from the bottom of your crepe sole shoe in the middle of July to get rid of the employee in the first place and then you're generally precluded from giving him a bad reference.