American police linked another crime to Web-based ads. Three burned human bodies were identified in Detoit, and names found on backpage.com ads. Which probably means they were sex workers, although CNN doesn't specify it.
This is related to the "Craigslist crimes", which have been in the media for some time. There's a combination of creepy factors, including meeting strangers, some level of criminality, and the growing reputation of these online ads for being unsavory.