They were all retired IIRC & they waited until the statute of limitations for those crimes had passed before revealing themselves. So it would have been difficult for the government to meaningfully retaliate without making significant changes to the legal system & it's not exactly an episode that the government wanted to draw attention to.
I suppose they could have gone for extra-legal methods, but after so much time the people with the motivation to make that happen (if it was possible at all) would have mostly retired too.