If the site is infringing on your companies brand, intellectual property, etc... then there are other paths your legal team could take but finding the people running the site may prove challenging. Most of these are just running atop of compromised blogs.
[1] - https://www.robtex.com/
[2] - https://bgp.he.net/
Domain registry, domain registrar, website host, website IP owner, DNS host, mail host, payment vendor (if you can tell), certificate authority, if they've got a phone number (especially a toll free number), etc. Some of these might the same places.
I think Microsoft and Mozilla might also run safebrowsing initiatives, worth checking with them too?
If you're in the US, be sure to report to federal law enforcement as well as local; although you might not get much action.