Payton- The media is your best bet as well as a few things I'll cover below. You have to remember you're dealing with the most corrupt, bureaucratic, pass the buck, gutless dog city in America. I wouldn't count on the DA's office for much help. They tend to only get involved in things that are cut and dried. Meaning things they won't have to work very hard on.
Zoning- A confusing thing about Las Vegas is depending on the location of the property is who has the juristicion. You have to deal with either the city or county. The City of Las Vegas Neighborhood Response is 702-229-6615 and the Clark County Public Response is 702-455-4191. If the property is in a gated community then the Homeowner's Association has to enforce the short term rental rules that I think they're probably violating.
Media- The two best bets here are Contact 13 at ktnv.com and Darcy Spears or Glen Meek at kvbc.com They are two solid reporters that I think would get on this but go to each of those sites and read more.
One more angle that I think would be a big help is to contact the State of Nevada Consumer Affairs Division at 702-486-7355. I have heard there are some good people in that section.
Our two local newspapers are piece of shit, fish wrap rags. Both the Las Vegas Review Journal and the Las Vegas Sun wouldn't sell one paper if they were in a city where anyone could read but they still might be of some use.
I wish you the best with this. If I can be of any help, let me know.