the Sonia Varaschin case

Not sure if the history is true (if the murderer met her at PlentyOfFish), but Legislation should had killed free online dating sites since years.
From Newspaper
From PlentyOfFish blog
The Online Dating Industry is performing like the Pharmaceutical and Cosmetic Industry before the USA Food and Drug Administration was created. 
There is no/weak Legislation, 
no ID verification, 
low reliable background checks, 
no Quality Norms. 
No one compatibility matching method is Scientifically Proven.