Clickbait at its finest, OP is just desperate to get traffic for their crappy site.
https://www.quora.com/Is-the-Sicilian-Hitmen-site-on-the-deep-web-real
It looks like it's a website that exists or existed, so how was this woman found? I suppose there are more other people who were found, so why only talk about this woman? What about the 12-year prison sentence, she can't he appeal to the higher courts?
My guess is that it was a phishing honeypot created by police to catch people who want to hire hitmen. As for how they tracked her, maybe they simply traced her BTC transaction if she didn't mix her coins - can be very easy if she bought coins with her credit card.