“Serious” Federal crime? He “lied” to two corrupt FBI agents. And the conversation had nothing to do with any crime. This case should have been tossed months ago. Why are these hacks so afraid of Flynn?
That is the important point. It is only illegal to lie to an FBI agent about something that is material to an investigation. If you are having a beer with some FBI agent and he asks you if you think his wife's dress is pretty you can say "sure, it looks great on her" even if you think it is ugly. But you can't lie about something material to an investigation.
In Flynn's case he didn't lie at all as far as anyone can tell from what has leaked out of the actual answers he gave.