Step one, find out their side of the story, read up on all the press you can find and try to see if there are any inconsistencies that proves your SO is lying or if the story seems to check out. If wrongly accused, inquire why she didn’t turn herself in and go to trial as it would likely not result in a conviction…if you’re not guilty, you’ve generally got nothing to worry about, right. If they copped to the crime but explained it, well, it would depend on the scenario.
If they killed an adult…well, who was the adult? If it was a truly despicable human being like a rapist, murderer or child molester, then I’d figure I KNEW I’d met Mrs. Right.
If they were accused of abusing a child, and couldn’t damn well explain it away, I might just take the law into my own hands…maybe I could find a poison condom?
If they’re accused of fraud, stealing a bunch of money, did they steal it from a charity or employer, or some money grubbing multinational corporation which makes its fortune on the backs of the working class and discards them like yesterday’s trash. If it’s the former, I turn her in for whatever reward I can get, if it’s the later, then I ask how much it is so I can know what style of living to become accustomed to.
If they turn out to be a scammer and I’m the next target, I’d find a way to turn the scam around on her and make a few bucks whilst giving her a taste of her own medicine.